Earlier quoted context omitted.
If you kill an app on the iOS, it stays dead until you launch it again, iirc.
it stays dead until the system decides to reload it. It may decide to do this for various reasons such a entering a geofence, significant location update, or push notification. But turning off background app refresh should prevent all of these things from turning on your app I think. Also low power mode can also be used as a sort of incognito mode because it stops all background activity to preserve battery.
I am not totally sure of geofencing.