Phone icon gone

The phone app cannot be deleted and cannot be disabled, so it is somewhere on the phone, either on another page of the Home screen or in a folder. Use the Search and search for “phone”. If it is in a folder the name of the folder will appear next to it. If there is no folder name it’s on a different page.

You can also try restarting your phone—>Restart your iPhone - Apple Support in the rare case that something got corrupted in iOS settings.

As a last resort: Settings/General/Reset - Reset home screen layout.