[theold]

NEW GUIDE for iOS 14+
Go into Setttings - Mobile Data - Turn Off
Go into Setttings - Bluetooth - Turn Off
For bonus reduction in levels, turn off background app refresh and location data.

OLD GUIDE for iOS 13
Go into Setttings - Bluetooth - Turn Off
For bonus reduction in levels, also switch to 3G mobile data by going into Settings - Mobile Data - Mobile Data Options - 3G.

https://www.youtube.com/watch?v=FCDmYimurwk

[EvertonDiehard]

This employee is a perfect fit for Apple, but I doubt she will be able to fix the iPhone's radiation issue:
 

[Buffybuffy]

China Apple will be frontal bite