What is RDS?
Amazon Relational Database Service (Amazon RDS) is meant to support relational database usage in cloud.
RDS lets us access MySQL, MariaDB, Oracle, SQL Server, or PostgreSQL databases and our current database operations can be performed in cloud.
As per AWS documentation the following are the databases or schemas capacity within DB instance,
RDS for Amazon Aurora has no limit imposed by software
RDS for MySQL has no limit imposed by software
RDS for MariaDB has no limit imposed by software
RDS for Oracle has 1 database per instance; has no limit on number of schemas per database imposed by software
RDS for SQL Server has 30 databases per instance
RDS for PostgreSQL has no limit imposed by software