Hmm, it looks like even a 7x7x7 doesn't need to have much. I guess it has a tiny amount larger edge and corner pieces though...
https://www.amazon.com/Shengshou-7x7x7-Cube-Puzzl-black/dp/B...
https://www.amazon.com/Shengshou-7x7x7-Cube-Puzzl-black/dp/B...
Apparently the 7-cube bulges slightly which helps to hide that the larger sized edges / corners