To Nha Notes | Dec. 29, 2023, 1:33 p.m.
If you want to know if a specific RDS change will cause downtime, both in cases of Single-AZ and Multi-AZ deployments, you can always refer to the AWS Documentation page: Modifying an Amazon RDS DB instance
https://stratusgrid.com/blog/how-to-perform-amazon-rds-upgrades-with-near-zero-downtime