hey rajaleidja ...
Lawrence tells me that when the Apple Apps are turned off ... they are not off but still on (you just can not see what they are doing).
I trust his assessment on the matter ... he is a learned person.
When Cellular Data is turned off pretty much nothing works (except for Text messages and Cell Phone) and you can not even make an outgoing verbal message (custom not default) for your voice mail when Cellular Data is turned off.
However ... that being said do you still have poor battery life when Cellular Data is turned off (have to turn off as well wi-fi, wi-fi assist, bluetooth, etc) so your smart phone then becomes a dumb phone that works and has battery life.
Plan Two ... is check for lint in your lightening port making for a bad connection (blow it out with clean canned air or maybe use electronic component cleaner with it turned off of course) and also turn off your cell phone except when you do not want to use it.
I know turning off your cell phone makes incoming calls much more difficult .. but see if the battery still drains down energy when it is off.
sumbuddie wear blind sea
😐