Postgres Database Performance is slow after upgrade from v15 to 17

After upgrading the Postgres Server from Version 15 to Version 17 running on RHEL 9, few of the SQLs changed the plan and running pretty slow. I am basically an Oracle DBA and thinking to perform the follow, but want to know what analyze option are best to calculate the stats. 1. Gather Statistics 2. Rebuilding the Indexes Beside above 2 options, if you have any further recommendations that would be highly appreciated.