Set a wifi chip in monitor mode, fire up wireshark, then see for yourself. Rather easy to do and once you do, you’ll learn to keep wifi off when you aren’t intentionally wanting it.
It's real limited in what it does, but it can turn wifi / bluetooth / other stuff on depending on time, location, the usual stuff.
I would love to have a real "Tasker" type app for iOS, but I doubt that will happen anytime soon.