Only Google Pixel 4 phones and later support the Quick Tap feature.
How Do I Turn on Double Tap Gesture on Android Phone?
TapQuick Tap(orQuick tap to start actionson Android 13).

Tap theUse Quick Tapslider to move it to the on position.
If you dont see it, your phone doesnt support the feature.
In Android 13, you’ve got the option to useQuick Tapto toggle the flashlight.

How Do I Turn off Double Tap Gesture on My Android?
Go back toSettings>System>Gestures>Quick Tapand move theUse Quick Tapslider to the offposition.
Why Should I Use Double Tap Gestures?

To activate one-handed mode, swipe downward from the center of the bottom half of the screen.
This restores the traditional Android button icons (Back, Home, and Recent apps).