Asking Suggestions regarding mysql optimization

Im running a dedicated server with around 20-25 sites, almost all of them running wordpress installations. Running it over a cpanel setup. For a while its mostly mysql eating most of the cpu and hitting high load times

mysql	0	  61.69(cpu)  6.92(ram)	/usr/sbin/mysqld

**Server config is**

Uptime             70 days 
Operating System   CentOS Linux 7 (Core) x64 File
Handles            14560 of 6511967 
Processes          342  
CPU Model          AMD Ryzen 5 3600 6-Core Processor
Ram                64GB

I am trying to improve this and came across mysql tuner, here is what it has to say after running mysql with performance schema on for 2 days or more. This isnt exactly my forte so the mycnf is just a blend of what I tried with an older mysqltuner suggestion but ive heard that the application would still require a human touch. Would appreciate some help in optimizing the settings.

>>  MySQLTuner 1.7.19 - Major Hayden 
 >>  Bug reports, feature requests, and downloads at http://mysqltuner.com/ 
 >>  Run with '--help' for additional options and output filtering

[--] Skipped version check for MySQLTuner script
[OK] Currently running supported MySQL version 10.3.27-MariaDB-log
[OK] Operating on 64-bit architecture

-------- Log file Recommendations ------------------------------------------------------------------
[OK] Log file /var/lib/mysql/server.name.here.err exists
[--] Log file: /var/lib/mysql/server.name.here.err(4M)
[OK] Log file /var/lib/mysql/server.name.here.err is readable.
[OK] Log file /var/lib/mysql/server.name.here.err is not empty
[OK] Log file /var/lib/mysql/server.name.here.err is smaller than 32 Mb
[!!] /var/lib/mysql/server.name.here.err contains 31430 warning(s).
[!!] /var/lib/mysql/server.name.here.err contains 23132 error(s).
[--] 60 start(s) detected in /var/lib/mysql/server.name.here.err
[--] 1) 2020-12-07  7:35:16 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 2) 2020-12-01 14:35:35 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 3) 2020-11-30 16:10:14 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 4) 2020-11-30 16:07:53 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 5) 2020-11-01  1:57:12 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 6) 2020-10-10 19:28:45 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 7) 2020-10-10 19:28:32 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 8) 2020-09-30  3:36:14 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 9) 2020-09-28 17:58:16 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 10) 2020-09-25 18:38:33 0 [Note] /usr/sbin/mysqld: ready for connections.
[--] 51 shutdown(s) detected in /var/lib/mysql/server.name.here.err
[--] 1) 2020-12-07  7:35:07 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 2) 2020-12-01 14:35:27 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 3) 2020-11-30 16:09:53 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 4) 2020-11-30 16:07:33 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 5) 2020-11-01  1:57:09 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 6) 2020-10-10 19:28:39 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 7) 2020-10-10 19:28:26 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 8) 2020-09-30  3:34:34 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 9) 2020-09-28 17:56:38 0 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 10) 2020-09-25 18:36:55 0 [Note] /usr/sbin/mysqld: Shutdown complete

-------- Storage Engine Statistics -----------------------------------------------------------------
[--] Status: +Aria +CSV +InnoDB +MEMORY +MRG_MyISAM +MyISAM +PERFORMANCE_SCHEMA +SEQUENCE
[--] Data in MyISAM tables: 2.1G (Tables: 1387)
[--] Data in InnoDB tables: 3.2G (Tables: 2207)
[--] Data in MEMORY tables: 586.4K (Tables: 3)
[OK] Total fragmented tables: 0

-------- Analysis Performance Metrics --------------------------------------------------------------
[--] innodb_stats_on_metadata: OFF
[OK] No stat updates during querying INFORMATION_SCHEMA.

-------- Security Recommendations ------------------------------------------------------------------
[OK] There are no anonymous accounts for any database users
[OK] All database users have passwords assigned
[!!] There is no basic password file list!

-------- CVE Security Recommendations --------------------------------------------------------------
[--] Skipped due to --cvefile option undefined

-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 2d 5h 57m 24s (167M q [862.613 qps], 2M conn, TX: 21024G, RX: 379G)
[--] Reads / Writes: 98% / 2%
[--] Binary logging is disabled
[--] Physical Memory     : 62.8G
[--] Max MySQL memory    : 43.5G
[--] Other process memory: 0B
[--] Total buffers: 5.0G global + 260.7M per thread (151 max threads)
[--] P_S Max memory usage: 104M
[--] Galera GCache Max memory usage: 0B
[OK] Maximum reached memory usage: 26.5G (42.17% of installed RAM)
[OK] Maximum possible memory usage: 43.5G (69.35% of installed RAM)
[OK] Overall possible memory usage with other process is compatible with memory available
[OK] Slow queries: 0% (324K/167M)
[OK] Highest usage of available connections: 55% (84/151)
[OK] Aborted connections: 0.00%  (55/2878495)
[!!] name resolution is active : a reverse name resolution is made for each new connection and can reduce performance
[!!] Query cache may be disabled by default due to mutex contention.
[OK] Query cache efficiency: 40.4% (102M cached / 254M selects)
[!!] Query cache prunes per day: 3479297
[OK] Sorts requiring temporary tables: 0% (11K temp sorts / 6M sorts)
[!!] Joins performed without indexes: 12813
[!!] Temporary tables created on disk: 66% (2M on disk / 3M total)
[OK] Thread cache hit rate: 98% (40K created / 2M connections)
[OK] Table cache hit rate: 95% (4K open / 4K opened)
[OK] table_definition_cache(2097152) is upper than number of tables(3862)
[OK] Open file limit used: 7% (2K/40K)
[OK] Table locks acquired immediately: 99% (13M immediate / 13M locks)

-------- Performance schema ------------------------------------------------------------------------
[--] Memory used by P_S: 104.0M
[--] Sys schema is installed.

-------- ThreadPool Metrics ------------------------------------------------------------------------
[--] ThreadPool stat is enabled.
[--] Thread Pool Size: 12 thread(s).
[--] Using default value is good enough for your version (10.3.27-MariaDB-log)

-------- MyISAM Metrics ----------------------------------------------------------------------------
[!!] Key buffer used: 24.9% (182M used / 734M cache)
[OK] Key buffer size / total MyISAM indexes: 700.0M/460.2M
[OK] Read Key buffer hit rate: 100.0% (1B cached / 41K reads)
[!!] Write Key buffer hit rate: 69.5% (804K cached / 558K writes)

-------- InnoDB Metrics ----------------------------------------------------------------------------
[--] InnoDB is enabled.
[--] InnoDB Thread Concurrency: 0
[OK] InnoDB File per table is activated
[OK] InnoDB buffer pool / data size: 4.0G/3.2G
[!!] Ratio InnoDB log file size / InnoDB Buffer pool size (0.78125 %): 16.0M * 2/4.0G should be equal to 25%
[!!] InnoDB buffer pool instances: 8
[--] Number of InnoDB Buffer Pool Chunk : 32 for 8 Buffer Pool Instance(s)
[OK] Innodb_buffer_pool_size aligned with Innodb_buffer_pool_chunk_size & Innodb_buffer_pool_instances
[OK] InnoDB Read buffer efficiency: 100.00% (102924116296 hits/ 102924220151 total)
[!!] InnoDB Write Log efficiency: 73.75% (4679039 hits/ 6344450 total)
[OK] InnoDB log waits: 0.00% (0 waits / 1665411 writes)

-------- AriaDB Metrics ----------------------------------------------------------------------------
[--] AriaDB is enabled.
[OK] Aria pagecache size / total Aria indexes: 128.0M/1B
[OK] Aria pagecache hit rate: 99.1% (277M cached / 2M reads)

-------- TokuDB Metrics ----------------------------------------------------------------------------
[--] TokuDB is disabled.

-------- XtraDB Metrics ----------------------------------------------------------------------------
[--] XtraDB is disabled.

-------- Galera Metrics ----------------------------------------------------------------------------
[--] Galera is disabled.

-------- Replication Metrics -----------------------------------------------------------------------
[--] Galera Synchronous replication: NO
[--] No replication slave(s) for this server.
[--] Binlog format: MIXED
[--] XA support enabled: ON
[--] Semi synchronous replication Master: OFF
[--] Semi synchronous replication Slave: OFF
[--] This is a standalone server

-------- Recommendations ---------------------------------------------------------------------------
General recommendations:
    Control warning line(s) into /var/lib/mysql/server.name.here.err file
    Control error line(s) into /var/lib/mysql/server.name.here.err file
    Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1
    Increasing the query_cache size over 128M may reduce performance
    We will suggest raising the 'join_buffer_size' until JOINs not using indexes are found.
             See https://dev.mysql.com/doc/internals/en/join-buffer-size.html 
             (specially the conclusions at the bottom of the page).
    When making adjustments, make tmp_table_size/max_heap_table_size equal
    Reduce your SELECT DISTINCT queries which have no LIMIT clause
    Before changing innodb_log_file_size and/or innodb_log_files_in_group read this: https://bit.ly/2TcGgtU 
Variables to adjust:
    query_cache_size (=0)
    query_cache_type (=0)
    query_cache_size (> 128M) [see warning above]
    join_buffer_size (> 2.0M, or always use indexes with JOINs)
    tmp_table_size (> 32M)
    max_heap_table_size (> 32M)
    innodb_log_file_size should be (=512M) if possible, so InnoDB total log files size equals to 25% of buffer pool size.
    innodb_buffer_pool_instances(=4)

**And here is what my.cnf currently has** **Note:** This is now edited based on suggestions by Wilson and Rick, Will save and restart mysql and get back to you guys with updates.

[client-server]

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

[mysqld]
# Logging and performance measurement here
log-error=/var/lib/mysql/ryzen.dogestream.com.err
# for enhanced slow query log
log_slow_verbosity=query_plan,explain
performance-schema=1


max_allowed_packet=268435456
max_heap_table=32M
tmp_table_size=32M
open_files_limit=40000


# Buffer sizes 
join_buffer_size=2M
key_buffer_size=700M
sort_buffer_size=2M


# InnoDB stuff goes here
innodb_file_per_table=1
innodb_buffer_pool_size=15G
innodb_log_file_size=16M
local-infile=0
# from 1024 to conserve 90% of CPU cycles used for function
innodb_lru_scan_depth=100
# should always match table_open_cache
innodb_open_files=9000


# Query stuff goes here
# from 128M to conserve RAM for more useful purposes
query_cache_size=0
# from 1 for OFF to avoid 3 million+ query cache prunes per day
query_cache_type=0
# from 2M to conserve RAM
query_cache_limit=0
slow_query_log=1
slow_query_log_file=mysql-slow.log
long_query_time=0.1


# It says cache it is here
table_definition_cache=-1
# from 3000 to reduce tables opened_tables count
table_open_cache=9000
# from 16 to accomodate your 84 concurrent users
thread_cache_size=256