You can use StandBy to turn your iPhone into a bedside clock, a photo frame, a display for viewing widgets or Live Activities in full screen, and more.
Open Settings > StandBy, make sure StandBy is turned on
Connect iPhone to a charge and set it down on its side, keeping it stationary
Press the side button
Swipe left or right to switch between widgets, photos, and clocks
When Night Mode is turned on for StandBy, the screen adapts to low ambient light at night and displays items with a red tint so that's it's not intrusive while you're sleeping.