We use pgagent, which has support up to the most recent version of postgres. I've also got it working on my AWS E2C instance, but not sure if it's available on Amazons out of the box databases (RDS).
I recently looked into this for one of my development teams. Pg_cron requires that you’re running version 12.x or higher. Unfortunately, my team is still running v.11.9 so we couldn’t use pg_cron.