I do not see the value proposition of the RDS rotation feature. RDS supports IAM auth, which gives you a token that is valid for 15 minutes, no need to worry about rotating passwords anymore: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Using...
There are several key restrictions on IAM token auth, not to mention that it may not be feasible to integrate in a given framework. It definitely solves the problem for manual access, but automated access may be a different story.
That said, there are a handful of examples available to handle RDS secret rotation through parameter store with Lambdas and custom cloudformation resources.
