In America, some carriers disable hotspot on the devices they sell and hold you hostage. There are many ways around this. The best way is to use OEM non carrier phones. Other options include pdanet and several other apps designed to bypass the carrier software locks. My graphene os hotspot works perfectly no matter what carrier I use
Edit: Oh, and you can forget it on iphones. Apple loves sucking carriers dicks and fucking you all over. They go out of their way to ensure the carriers are robbing you before allowing hotspot use
I didn’t know Apple also did this. That is ridiculous