App uninstall and reinstall

See these articles:

Delete apps on your iPhone, iPad, and iPod touch - Apple Support

Download apps and games on your iPhone or iPad - Apple Support

If you are not given the option of uninstalling an app, go to Settings>Screen Time>Content & Privacy Restrictions>iTunes & App Store Purchases and make sure everything is allowed.

Long press the icon for the application on your iPhone's home screen> select delete the app from the pop-up> open your iPhone's Apple Store App (if you can't find it on your screen, use your thumb to swipe right to left or vice versa, and use the text box search feature to find the app)> once your apple store app is open search for the app you want> select the arrow to redownload.