When I want to round out a corner, I draw an arc and then push/pull to drop the excess out of existence. I had seen a video where someone (using pro) double tapped on another corner and the program auto filled a copy of the first arc.
I tried it and it didn’t work, even though other double tap to repeat functions work (push/pull, offset, etc). I thought ‘just hasn’t made it into the app yet’.
But today, while multitasking, I absently tapped it with my finger instead of the pen and it works.