FACE ID NOT WORKING ON IPHONE X

If you still need help, reset Face ID, then set it up again. Go to Settings > Face ID & Passcode and tap Reset Face ID. Then tap Set up Face ID to set it up again. If you can't enroll your face, take your device to an Apple Retail Store or Apple Authorized Service Provider or contact Apple Support.

If Face ID isn't working on your iPhone or iPad Pro - Apple ...

Follow ALL the steps provided in this support article:--> If Face ID isn't working on your iPhone or iPad Pro – Apple Support

If the issue persists, contact Apple Support directly, using this link:--> Get Support

Regards

Giulio