According to this microsoft support page (shown in the animated gif at right below)
To use keyboards shortcuts to copy formatting, press COMMAND + SHIFT + C to copy the formatting, select the text that you want to apply the formatting to, and then press COMMAND + SHIFT + V to paste the formatting
However, as shown in the animated gif below (click for better detail), it does not work for me. I describe what I'm doing with the keyboard with the text in black, blue, and red.
Notice at the end that I am able to paste format using the format painter tool, but my goal is to use keyboard shortcuts to do this. To demonstrate that this is not due additional custom shortcuts on my system, I have the shortcuts portion of the System Preferences open and you can also see the normal paste shortcuts in the Edit menu during the animated gif.
I'm using an updated Microsoft Word for Mac version 16.29.1 on an Office 365 subscription with Mac OS X 14.6