@Rediikid Well, the easiest and fastest way to get rid of all trackers and ads from an app would be to use Lucky Patcher or APK Editor Pro to DISABLE the internet on the app.
But if the app needs internet to work then scratch that. Every app is made different so some arn't as easy to remove analytics and stuff. I can't give you a direct method due to this. The best advice I have is to do some deep searching in APK Editor Pro with the app and learn the app to be able to remove its junk.
@glitcher32 just so I could understand a bit do u know how I could do it to Firefox? Like fennec I guess