When you raise the phone, the screen wakes up.
1.Go to
Settings > 
Always-on display & Lock screen.
2.Tap
to enable Raise to wake.
1.Go to
Settings > Always-on display & Lock screen.2.Tap
to enable Raise to wake.Double tap to wake or turn off screen when device is locked
You can double tap to turn the screen off only when pre-installed themes are applied.
1.Go to
Settings > 
Always-on display & Lock screen2.Tap
to enable Double tap to wake or turn off screen when device is locked.