I want to change my display settings from "Extended Display" to "Main Display" with a keyboard shortcut. Is there a way to do this programmatically? You can press cmd+F1 to toggle the Mirror settings, but I haven't found a way to toggle the extended display function.
I think your best bet is probably displayplacer, which you can install via Homebrew (or probably MacPorts), or directly from the site. You can then do things via the shell (or a Keyboard Maestro shell script action) to change the displays.
You'd set the origin of the display you wanted to be the main display as 0,0, which macOS will then interpret as the main display.
I used to use this when I used my laptop as my primary Mac some years ago, but I haven't tried it recently ... but I think it'll do what you want, and more easily than GUI scripting.
-rob.
Plenty of "A" but not so much "I" in that last post...