Face ID has been the default method for unlocking, or securing purchases in an iPhone since the iPhone X days and replaced the Touch ID except in the iPhone SE 2020. As more and more users continue to switch to iPhones, not everyone would know how to set up Face ID.
Here is a tutorial for how to set up Face ID in your new iPhone for unlocking your device or making purchases:
Make sure your iPhone’s front facing camera present in the notch up top is clean and uncovered.
Go to Settings > Face ID & Passcode. If asked, enter your passcode.
Tap Set Up Face ID and make sure that you’re holding your device in portrait orientation.
Now, Position your face inside the frame and gently move your head to complete the circle.
When you finish the first Face ID scan, tap Continue.
Now, Gently move your head to complete the circle for a second time and tap Done.
Now you can raise your iPhone to tap to wake it and when you look at it, the lock on the top will unlock meaning you can now unlock your iPhone as it has identified your face.