That would be a good size for any adult gtp female. My male is in a 24*24*22 and uses the space very well. They are pretty active at night. My biy cruises each night and he even swims in his water bowl. He is a joy to watch. Many people have gotten away from the cube cages and are going to the 36 inch long with a shorter height. Sometimes the rhp will habe a hard time keeping the top perch at a good temp while still sending heat to the lower levels so the shorter cages make this a bit easier. My cage is in a heated room so i dont have to worry about the rhp creating a good ambient temp and only need it for the hotspot.

I would recommend getting the cage set up far in advance because it may take some time to get it right and chondros can be sensitive compared to others.