I have bought Houdini 6 pro ( ChessBase version ), for the primary purpose of practising by playing games against Houdini 6 pro (and other engines I own) I cannot figure out how to play a game against it (Not friendly game with dumbed down engine) . I want to play games with the engines full capacity (using ChessBase GUI) Is this possible or is ChessBase just a database program. Thanks in advance.
Chessbase is indeed just a database program, albeit a very powerful one. If Houdini doesn't already provide it then you will need some kind of front end to play games against it.
One of the best free ones is Scid vs PC. This is available for download on Sourceforge and if you need more help getting started with it then there is much useful information on the Watford Chess Club website. There it explains in great detail what you need to do to get Scid to use other engines like Houdini.
You cannot play games against engines in ChessBase. ChessBase is just a database program.
ChessBase community has released DeepFritz which is also a GUI where you can play even rated games with the engine you want.
Deep Fritz 16 is the latest version of it. Check https://en.chessbase.com/post/fritz-16-your-companion-and-trainer for more information.