Google Pixel phones have a secret button. Here’s how to find it (and use it)

To access Quick Tap, open up Settings and scroll down to System > Gestures. Then, go to Quick Tap to start actions. The page will display an animation of how to use the feature and a list of what you can activate, including taking a screenshot, opening Google Assistant, playing or pausing media, showing notifications, and opening a desired app.

Also: How to make your Pixel phone automatically decline robocalls

Personally, I have Quick Tap set to turn on or off my flashlight.