Convert a non PDB 19c database to a PDB Database

Hello All

We have a few 19.21 databases running on Exadata X7

we dont have a multi tenant setup / CDB / PDB anywhere on the system and we are brand new to the multi tenant concept / architecture.

We are planning to slowly convert / migrate / move our stand alone databases to multi tenant architecture and seeking some basic / foundational knowledge to do that. What is the first thing we need to do to convert one of our test databases into a PDB?

Do we need to first create a brand new database and create it as CDB? (so that we can then move all the current databases as PDB databases as part of that CDB? )