Hell friends, everyone is waiting for Android 11 so before we get it officially, test one of its future before we get. So many users demanded double tap to sleep so i searched it and found one best app for it, but not just that function but many more. It is from xda devlloper site. Some info from site below. Go to link and read full article and download apk.
Tap, Tap is a port of the double tap on back of device gesture from Android 11 to any Android 7.0+ device. It allows you to use the gesture to launch apps, control the device (including pressing the home, back and recents buttons), take a screenshot, toggle the flashlight, open your assistant and more. Using "gates", you're able to block the gesture from working in scenarios such as when the screen is off, when you're on a call, when an app is open and more. It uses an accessibility service to run these tasks and stay running in the background. Tap, Tap uses the same machine learning code and TensorFlow models from the Android 11 builds with the gesture, with code directly lifted from SystemUIGoogle where needed. You can pick from three models in the settings: Pixel 3 XL, Pixel 4 and Pixel 4 XL; allowing you to choose the one that fits your device best. Machine learning allows the gesture to be more accurately detected, and reduces the chance of accidental interactions
