I can't download apps from App Store on iPhone

try this:

Settings, Screen Time, Content and Privacy Restrictions, iTunes and App Store Purchases, Installing Apps, Allow “on”

or turn screen time completely off.

All the other options are in the article below

If you can’t download or update apps on your iPhone or iPad

I need help I can’t, download anything on my iPhone or iPad at all tells me that there are restrictions, on my phone I can’t sign out or anything.

Look at the answers above