What’s the function iod FaceApp

Here are instructions on how to set up Face ID:

Use Face ID on your iPhone or iPad Pro - Apple Support

Here are helpful hints to try

If Face ID isn't working on your iPhone or iPad Pro - Apple Support

If after trying all these tips, it still does not work, here is what to do:

Get service

If you still can't enroll your face, contact —>> Apple Support.

Only a trained technician should service your device. Improper repair, modification, or use of non-genuine Apple components in the laser systems might prevent the safety mechanisms from functioning properly, and could cause hazardous exposure and injury to eyes or skin.