Most of the new upcoming iPad Pro-centric features also apply to iPhones and Macs. On the other hand, some might work best with iPadOS 16's target form-factor; furthermore, there are some potentially long-awaited additions, which include a new Desktop-Class App initiative that benefits Apple tablets.
https://www.notebookcheck.net/iPadOS-16-is-rated-to-make-Apple-s-flagship-tablets-more-powerful-Pro-devices.625787.0.html