To do Alt + H O on Mac in Excel, download and install Accelerator Keys, then press Option, followed by H and O.
Command: Format Menu
This is how to do Alt + H O on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + H O opens the Format dropdown menu with options to adjust Row Height (H), AutoFit Row Height (A), Column Width (W), AutoFit Column Width (I), Default Width (D), Hide & Unhide (U), Rename Sheet (R), Move or Copy Sheet (M), Tab Color (T), Protect Sheet (P), Lock Cell (L), and Format Cells (E).