To quickly unlock your screen and save time, simply tap the screen twice to illuminate it, making unlocking easy. This also helps to protect the power button for long-lasting use.
To enable the double tap to wake feature on your Asus Zenfone 3 ZE520KL, follow these steps:
Step 1: Go to 'Settings'.

Step 2: Select 'ZenMotion'.

Select 'ZenMotion'.
Step 3: Enable and choose 'Touch Gestures'.

Enable and choose 'Touch Gestures'.
Step 4: Turn on 'Double Tap to Wake'.

Turn on 'Double Tap to Wake'.
Best wishes for success.