If an iPhone 11 is frozen and the screen does not respond, a force restart can reboot it without erasing your data.
- Press and quickly release Volume Up.
- Press and quickly release Volume Down.
- Press and hold the Side button.
- Keep holding until the Apple logo appears, then release the Side button.
Do the button presses in that order and avoid holding the volume buttons during the last step.
If the iPhone does not respond after a force restart, connect it to a charger and try again after it has charged. Repeated freezing can be caused by software, low free storage, or hardware problems and may require further troubleshooting.