Support for native backup and … – docs.aws.amazon.com

By using native backup and restore for SQL Server databases, you can create a differential or full backup of your on-premises database and store the backup files on Amazon S3. You can then restore to an existing Amazon RDS DB instance running SQL Server. You can also back up an RDS for SQL Server database, store it on Amazon S3, and restore it in other locations.

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Appendix.SQLServer.Options.BackupRestore.html