It's on 9.5 which is reaching EOL. I suspect we could go straight to latest without much problem.
From amazon:
If you do not upgrade your databases before February 16, 2021, RDS will upgrade your PostgreSQL 9.5 databases to PostgreSQL 12 during a scheduled maintenance window between Feb 16, 2021 00:00:01 UTC and March 16, 2021 00:00:01 UTC. On March 16, 2021 00:00:01 AM UTC, any PostgreSQL 9.5 databases that remain will be upgraded to version 12 regardless of whether the instances are in a maintenance window or not.
It's on 9.5 which is reaching EOL. I suspect we could go straight to latest without much problem.
From amazon: