How do you turn on Face ID

Open up Settings and scroll a bit down until you see Face ID and code. After tapping it and typing in your code you should be able to add your face and use it as a Face ID. However if you can't complete it, or it gives you some kind of error, it is possible that the Face ID is not supported on your iPhone. Now that may be caused by having the display or camera changed or some other problem. If it doesnt work go to a repair shop.

If you are getting the FaceID Disabled alert you’ll have get Apple to service the phone.