(I've got a samsung so idk if it works on iPhones)
1,turn on mobile data
2. tap and hold on the mobile data icon in the quick settings menu (or just go 6o mobile data from settings)
3. go to the data usage menu
4. you'll see a settings icon, click on it and enable the data limit (and the data warning of you want)
5. set how much data you want to use per month, and a warning when u use a certain amount of data if u want.
.
idk if that was a good explanation, its 5 am and I haven't slept all night
1,turn on mobile data
2. tap and hold on the mobile data icon in the quick settings menu (or just go 6o mobile data from settings)
3. go to the data usage menu
4. you'll see a settings icon, click on it and enable the data limit (and the data warning of you want)
5. set how much data you want to use per month, and a warning when u use a certain amount of data if u want.
.
idk if that was a good explanation, its 5 am and I haven't slept all night