Use your passcode instead.
If Face ID does not recognize your face, your iPhone will prompt you to enter your passcode instead. Typically, after two failed Face ID attempts, the passcode entry screen appears automatically. However, there are several situations where Face ID may not even attempt to authenticate and will require a passcode immediately.
These include:
- Restarting your iPhone
- Not unlocking your iPhone for more than 48 hours
- Five consecutive failed Face ID attempts
- Initiating an Emergency SOS call
- Changing your Face ID settings
- Your iPhone has been locked remotely using Find My iPhone
- Not using Face ID to unlock your iPhone in the last 4 hours (but using it for other features)
If Face ID continues to fail, you can swipe up from the bottom of the screen and tap "Use Passcode" to unlock your iPhone manually.