To do Alt + H + S + S on Mac in PowerPoint, download and install Accelerator Keys, then press Option, followed by H, S, then S.
Command: Quick Styles
This is how to do Alt + H + S + S on Mac in PowerPoint with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with PowerPoint.
Alt + H + S + S opens the Quick Styles gallery, displaying preset shape styles with various combinations of fill colors, outlines, and effects that you can apply to the selected shape with one click.