To do Alt + J I G on Mac in Excel, download and install Accelerator Keys, then press Option, followed by J, I, G.
Command: Pens
This is how to do Alt + J I G 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 + J I g opens the Pens gallery in the Draw tab. This gallery displays all available pen styles including different colors, thicknesses, Pen types. You can select a pen to use for drawing or highlighting on your spreadsheet.