Amazon Relational Database Service (Amazon RDS) for Oracle now supports converting existing Oracle Database 19c instances from the non-multitenant to the multitenant database architecture. DB instances using the multitenant architecture consist of a container database (CDB) with a single pluggable database (PDB). A PDB is a set of schemas, schema objects, and non-schema objects that logically appears to a client as a non-CDB.
Source:: Amazon AWS