Amazon RDS for SQL Server supports minor versions 2014 GDR, 2016 GDR, 2017 CU31 GDR, and 2019 CU23

New minor versions of Microsoft SQL Server are now available on Amazon RDS for SQL Server, offering performance and security fixes. Amazon RDS for SQL Server supports the new minor versions for SQL Server 2014, 2016, 2017, and 2019 on the Express, Web, Standard, and Enterprise Editions.

Source:: Amazon AWS