Camera icon missing
How do I get back the missing iPhone camera icon?
iPhone XS, iOS 13
Return iPhone settings to their defaults - Apple Support
Go to Settings > General > Reset...Reset Home Screen Layout... Returns the built-in apps to their original layout on the Home screen.
Maybe it was hidden by mistake and is now attached to another app in a folder so open each app one at a time and if you find it just drag it out...Try this first before you try the above...
How to move apps and create folders on your iPhone, iPad, or iPod touch - Apple Support
Also see if it is not disabled in Screen Time...