Hi Nikita_111,
To clarify, when you say your iPhone overheats, does it show a warning it has gotten too hot and needs to cool down?
If so, when specifically does. this most happen? For example, while charging? Or playing a game? There's a few things that can cause the iPhone to warm up and would be expected behavior from the device.
"Your device might get warm
You might notice that your device feels warmer when you:
- Set up your device the first time
- Restore from a backup
- Wirelessly charge your device
- Use graphics-intensive or processor-intensive apps, games, or features, including augmented-reality apps
- Stream high-quality video
These conditions are normal, and your device will return to a regular temperature when the process is complete or when you finish your activity. If your device doesn't display a temperature warning, you can keep using your device."
You can see more info about how your iPhone regulates temperature here:
Cheers!