Turn Off Your iPhone
If your iPhone is already too hot and you can’t be in a cooler place right now, you can help it cool down by turning it off.
After you turn it off, disconnect it from the power source and remove any accessories or cases it has. Wait until it cools down and turn it on again.
To turn your iPhone off, if you have an iPhone with Face ID, press and hold the side button and one of the volume buttons at the same time. For iPhones with Touch ID, simply press and hold the side button.
Then, slide the Power Off Slider to the right. Wait until your iPhone cools down, and then turn it on again by pressing and holding the side button until the Apple logo appears on your screen.