Comment by tfoil2

Yes, turning Background App Refresh off goes a long way toward achieving this (and saving battery). Even with Background App Refresh turned off though, some activities may continue, particularly Location, audio, voice, and the like [https://developer.apple.com/library/content/documentation/iP...]. This is why it's Location "While Using" is important. It also looks from OP's comment [https://news.ycombinator.com/item?id=14502423] that (some of?) these features will be more prominently displayed to users. This is good, users should have complete knowledge and control of their devices, particularly as it affects privacy.