If the steps above don't work, you may have a hardware issue, such as a damaged digitizer or internal liquid damage.
Official screen replacement for an iPhone 11 typically costs around $199 out-of-warranty or $29 if you have AppleCare+.
Keep holding even when you see the "Slide to power off" slider.
Third-party accessories can sometimes cause "ghost touches" or unresponsiveness due to interference or physical pressure.
This is the most effective solution for a frozen screen. It reloads the device's code without deleting any of your personal data. Quickly press and release the button. Quickly press and release the Volume Down button. Press and hold the Side button (power button).
Some heavy-duty cases can put pressure on the edges of the display, causing it to freeze. Try using the phone without the case.