Safari disappeared on my iPhone

The Safari app is not one of the apps that can be deleted but it can be removed from the Home Screen. Go to the App Library (swipe left past your last Home Screen). From there you can touch and hold an app and slide it to the Home Screen.

Another reason for it not being visible is due to a restriction. Go to Settings and tap Screen Time, tap Content & Privacy Restrictions, tap Allowed Apps & Features, and turn Safari to Allow. Also see the following Apple Support article for more information: Use parental controls on your child's iPhone or iPad - Apple Support