To do Alt + P M on Mac in Excel, download and install Accelerator Keys, then press Option, followed by P and M.
Command: Margins
This is how to do Alt + P M 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 + P M opens the Margins menu with preset margin options for your printed pages. You can quickly select Normal, Wide, or Narrow margins, or access custom margin settings for precise control over your print layout.