D
Look-up Xara, which has had this for many years, and is highly useful. Inkscape/Corel took much of it's UI-UX from Xara. Xara was on the verge of going Open Source. At least for Linux. Until it reneged.
Double-clicking the transform origin point converts circle to square, or rectangle to ellipse, and vice versa. Double-clicking the corner node (Xara has additional corner nodes within the bounding box for all objects) transforms the shape into hexagon. And you can use the dedicated polygon tool to change this in any way. It is highly efficient. I'm going to catalogue all the possible improvements over the next few months and post in the forum. Hopefully, @VectorStyler, you'll find some ideas you've not considered.