Play games on my Ipad without an app.

You seem to be confused. It is the developer of the app that includes in-app purchases, Apple does not do that. If you do not like an app that includes in-app purchases, then don't play it. Epic used to have their games in the App Store until they decided to sue Apple because they did not want to follow the rules and wanted to create their own App Store. That is a choice they made and apparently they did not bother asking how you felt about their decision. It really is that simple!

If you don't want to use an app, then you would need to go to their website and see if you can play their games from there.

In-App purchases are created and managed by the game developers, Apple has, nothing to do with it.