[kulhur]

nircmd has this functionality (haven't tried it myself so no guarantees)

https://nircmd.nirsoft.net/setprimarydisplay.html

It also has a bunch of other useful features like changing the default audio device (something I use every day) and opening the CD tray ;)

Anyway, it's the best tool I've used for scripting stuff on windows. No GUI, just a bunch of useful or less useful command line utilities.