How do you make a rounded corner in CC?

[WillAdams (William Adams (Carbide 3D))]

Does this thread help?

Symmetrical Rounded Edges Issue

lower than circle by its radius? not sure what you mean by that, but the rest makes sense.

Or this one?

How to access the Boolean function?

ok so if i understand, make a square overlapping the exact corner, then a circle inside that square? Sorry very new to this so stick with me. As for the rectangles, how should they be overlapped? Images would be amazing if it’s not to much to ask. Either way thank you so much.