Create a workspace / database space in single database

For instance, think as-

I have my enterprise database 'D'.

A company 'X' is getting registered with my company, so I create a separate workspace/ database space for 'X' in my database 'D'.

So when 100 companies gets registered with my company, I have 100 separate workspace / databases space in 1 central database.

In any RDBMS, is it possible to create a workspace / database space in single database ?