To do so, hold down the Power or Side buttons for a few seconds until the Slide to Power Off screen appears. To turn off the gadget fully, move the slider to the right. After 30 seconds, tap the Power or Side button once more until you see the Apple logo.

You can also perform a forced restart. Here's how it works:

Quickly press and release the Volume Up button. Then, quickly press and release the Volume Down button. Finally, hold down the Side or Power button until you see the Apple logo.

check if this method work or not