I can no longer update some apps on iPad Pro

[JohnAtl]

You could try offloading the apps, which preserves your data (according to the interwebs).

Running out of iPad Storage Even with Photos Optimized

If you go into Storage, there is an option to Offload unused apps. He can also manually offload apps. Offloading is different from deleting, in that it saves the app’s data. Reinstalling from Storage afterward should put him back in business. He could also move his photos to the cloud to free up space.