What is isolation level of autocommit?

I'm trying to make sense from "autocommit" concept. Originally I've heart about it in the context of Java JDBC API [Connection.setAutoCommit(boolean autoCommit)](https://docs.oracle.com/javase/8/docs/api/java/sql/Connection.html#setAutoCommit-boolean-) Quick search revealed that the term is not specific to JDBC, PostgreSQL refer to "autocommit" too: https://www.postgresql.org/docs/current/sql-start-transaction.html > In the standard, it is not necessary to issue START TRANSACTION to start a transaction block: any SQL command implicitly begins a block. PostgreSQL's behavior can be seen as implicitly issuing a COMMIT after each command that does not follow START TRANSACTION (or BEGIN), and it is therefore often called **“autocommit”**. Other relational database systems might offer an **autocommit** feature as a convenience. If it is widespread **what is isolation level of autocommit mode**? Conceptually as we have only one SQL statement before implicit COMMIT *isolation levels almost make no sense for autocommit*. Only READ UNCOMMITTED might influence the result, other anomalies are defined in term of a sequence of SQL statements. Can I alter autocommit isolation level to / away from READ UNCOMMITTED?