How to add “delete app” to iPhone storage to remove apps from iPhone?

Tap on an app in iPhone storage and the option to delete is right there.

Are you saying in Settings > General > iPhone Storage > [app name] you do not get the option to delete an app?

If so.. go to Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Deleting Apps

make sure that's set to 'Allow'

Sorry, but your question makes absolutely no sense.