Apple phone icon

Use App Library to search the Phone app, see -> Organize the Home Screen and App Library on your iPhone

Organize the Home Screen and App Library on your iPhone - Apple Support           

• If you have find the Phone app, tap & hold on the app, then drag to the Home screen / Phone Dock & drop it.

I’m sorry to hear that you accidentally deleted your phone icon. Here are some steps you can try to restore it:

1. Reset your Home Screen Layout: You may recover the default Home Screen layout by resetting it. To do this, go to Settings > General > Reset > Reset Home Screen Layout.
2. Reset Screen Time Settings: If you have enabled Screen Time on your iPhone, it may be causing the issue. To reset Screen Time settings, go to Settings > Screen Time > Turn off Screen Time > Turn on Screen Time.
3. Restart iPhone: Restarting your iPhone can help fix many issues, including missing icons. To restart your iPhone, press and hold the power button until you see the “slide to power off” option. Slide it to turn off your iPhone and then press and hold the power button again until you see the Apple logo.

[Edited by Moderator]