Open iphone by face id while using mask with apple watch

You need:

• An iPhone that uses Face ID (iPhone X or later) and has iOS 14.5 or later
• An Apple Watch Series 3 or later with watchOS 7.4 or later

Read here => Unlock your iPhone with Apple Watch when you're wearing a face mask - Apple Support

How to unlock your iPhone with your Apple Watch

1. Make sure that you're wearing a mask and that your Apple Watch is on your wrist and unlocked.
2. Wake your iPhone by raising it or tapping its screen.
3. A glance at your iPhone to unlock it. Then you can slide up from the bottom of your iPhone screen to begin using it.

Unlock your iPhone with Apple Watch when you're wearing a ...