How to use the Samsung Galaxy smartphone face recognition lock screen

Face recognition
You can enable Face Recognition to unlock your screen. To use your face to unlock
your device, you must set a pattern, PIN, or password.

• Face recognition is less secure than Pattern, PIN, or Password. Your device could
  be unlocked by someone or something that looks like your image.
• Some conditions may affect face recognition, including wearing glasses, hats,
  beards, or heavy make-up.
• When registering your face, ensure that you are in a well-lit area and the camera
  lens is clean.

1. From Settings, tap Security and privacy > Screen lock and biometrics >
   Face recognition.
2. Follow the prompts to register your face.

Face recognition management
Customize how face recognition works.
◌ From Settings, tap Security and privacy > Screen lock and biometrics >
Face recognition.

• Remove face data: Delete existing faces.
• Add alternative appearance to enhance recognition: Enhance face
  recognition by adding an alternative appearance.
• Face unlock: Enable or disable face recognition security.
• Stay on Lock screen until swipe: When you unlock your device with face
  recognition, stay on the Lock screen until you swipe the screen.
• Require open eyes: Facial recognition will only recognize your face when
  your eyes are open.
• Brighten screen: Increase the screen brightness temporarily so that your
  face can be recognized in dark conditions.
• About face recognition: Learn additional information about securing your
  device with face recognition.