I deleted safari app. How do I reinstall? On iPhone

The Safari app is not one of the apps that can be deleted but with iOS 14 it can be removed from the home screen. If you have iOS 14, go to the App Library (swipe left past your last home screen). From there you can touch and hold an app and slide it left back 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. See: https://support.apple.com/en-us/HT201304#allow-apps

Safari cannot be deleted from an iPhone.

If you removed it from the Home Screen, swipe to your last Home screen to access App Library and drag it back to a Home Screen.

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