When the screen is on, you can use
Face Unlock to quickly unlock
HTC U12+ by simply looking at the front camera.
Home screen, swipe up and then tap
If you haven't already set up a screen lock, you'll be asked to choose and set up a backup pattern, PIN, or password for unlocking your phone.
Setting a screen lock.
If prompted, choose how you want to show notification content when your phone is locked, and then tap
Register face data, and then read the tips and reminders.
Next and follow the onscreen instructions to scan your face.
Turn on to enable
Note: Face Unlock is less secure since your phone could be unlocked by someone or something that contains or looks like your image. If you have concerns, use other more secure authentication methods such as a screen lock pattern, PIN, or password.
Or use your fingerprint for unlocking your phone.