Make Face ID More Secure 

If you have an iPhone with Face ID, you can add another layer of security by requiring it to check that you’re actually paying attention. 

With this feature enabled, your iPhone will use its TrueDepth camera to ensure you’re actually looking at your iPhone when you try to unlock it. That way, even if you’re holding your iPhone in front of your face, it will not unlock until you start looking at it.

This is useful in cases where someone wants to try to unlock your iPhone without your knowledge or when you’re asleep. 

This should be enabled by default, but here’s how to make sure you’re using this feature:

1. Open the Settings app.
2. Scroll down and open Face ID & Passcode.
3. Enter your passcode.
4. Scroll down and under Attention, turn on Require Attention for Face ID.