There is no simple answer or solution to your question but here are some facts.
  • An app installed on iOS or iPadOS device automatically installs on all compatible iOS/iPadOS devices on the same Apple Account,
  • Deleting an app on an iOS/iPadOS device does NOT delete the corresponding app on other iOS/iPadOS devices on the same Apple Account.
  • Some apps are iOS or iPadOS specific and will only install on an iPhone or iPad and must be purchased and installed seprately on each OS, but not necessarily on each device.
  • In-app purchases in games like hints, magic coins, [/i]etc.[/i] generally are good only for the device they are purchased on.
  • In-app purchased Subscription services purchased on one device generally apply on multiple devices but have to be manually activated or renewed on devices other than the one they were purchased on.
  • The app store remembers apps you have purchased or installed and if you delete a given app from one or all your devices and later decide you want it on the same or a different device on the same Apple account, it can be downloaded without purchasing it again. In the same manner the app store remembers in-app purchases but they must be renewed to turn them on if an app is re-installed.
  • Using Settings > General > iPhone Storage you can delete an app but save all its settings and data or delete the app along with all of its settings an data.
  • In iOS 14 you can delete an app from the desktop, but it remains available for use in the App Library
MY SUGGESTION
  • iOS/iPadOS apps tend to update frequently or not at all and only currently installed apps are updated. I recommend leaving automatic update turned on and just delete those apps you do not want on each particular device.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein