Steps to reproduce:

1. Follow: https://git.zabbix.com/projects/ZBX/repos/zabbix/browse/templates/db/postgresql_agent2/README.md?at=refs%2Fheads%2Frelease%2F6.2
2. Setup PgSQL server to use optional TLS (with mandatory we will just fail);
3. Check PgSQL stats:

SELECT datname,usename, ssl, client_addr 
  FROM pg_stat_ssl
  JOIN pg_stat_activity
  ON pg_stat_ssl.pid = pg_stat_activity.pid;

Result:
Suggested user will not use encryption.

Expected:
Able to set tls options for the plugin like:

Plugins.PostgreSQL.TLSConnect=required

This is not a feature request, this is a bug in design. Create official template, implement encryption, and they are cannot be used until you manually re-create the template to support {$PG.SESSION} variable in all keys.