For rectangles, you can adjust the Width, Height, Corner Style (Regular, Rounded, Inverted, or Clipped), Corner radius, and Inner border width.
The Corner radius is only available when Rounded, Inverted, or Clipped is selected.
DesignCentral for Rectangle
Regular with Inner Border
Rounded without Inner Border
Inverted without Inner Border
Clipped with Inner Border
Editing Shapes Using DesignCentral