How do I update my apps in ios13?

You can tap on your icon at the top right of the screen in the app store app and if you scroll down you will find a section with the heading updates. Your updates live here now. You can also force/haptic touch on the App Store app and select updates.

You do.

Start App Store app > tap your avatar (top right) > see here and to refresh the screen drag down with 1 finger