Press and hold the Side button and either Volume button until the power-off slider appears
If the screen is unresponsive, press and quickly release Volume Up
Press and quickly release Volume Down
Press and hold the Side button until the Apple logo appears, then keep holding until the power-off slider or shutdown option appears
Use AssistiveTouch if it is already enabled
Go to Settings, then General, then Shut Down if the touch screen still works partially
If the iPhone is frozen, force restart it instead of powering it off
For iPhone 8 and later, press and quickly release Volume Up, press and quickly release Volume Down, then press and hold the Side button
For iPhone 7 and 7 Plus, press and hold the Side button and Volume Down button
For iPhone 6s and earlier, press and hold the Home button and Side button
If buttons do not work, let the battery drain completely
If needed, connect the iPhone to a computer and use recovery mode or DFU mode