Press and hold the Side button and either Volume button until the power-off slider appears, then use AssistiveTouch, Voice Control, or an external accessibility device to drag the slider
Use Siri and say “Turn on Voice Control” or “Turn on AssistiveTouch” if already enabled, then use it to access the power-off slider
Go to Settings > Accessibility > Touch > AssistiveTouch and turn it on if you can use another input method
Use AssistiveTouch > Device > Lock Screen, then press and hold the Side button and a volume button to bring up the power-off screen
If your iPhone has a Home button, press and hold the Side button until the power-off slider appears, then use AssistiveTouch or Voice Control to operate it
Let the battery drain completely until the iPhone powers off
If the screen is unresponsive and you need a force restart, press and quickly release Volume Up, press and quickly release Volume Down, then press and hold the Side button until the Apple logo appears