@h6477801471, ok, if you put MultiMonitorTool.exe in d:\tools, then make your command this:
d:\tools\MultiMonitorTool.exe /TurnOff 1
Or you could do this so you can say, Alexa, turn monitor off, and Alexa, turn monitor on.
978faec6-3792-4b24-83b9-f78eb6bed2a6-image.png
If you specify the path (d:\tools) to the .exe file in your command you don't have to put d:\tools in your PATH variable.
If you want, you could turn the projector on and off with a smart plug instead. You'd create 2 commands, and associate each one with an Alexa routine that flips the smart switch off and on. The problem is I don't think you're supposed to abruptly turn projectors off because the fan needs to run to cool the bulb down. I'm not sure though if that's still a concern these days.
I made a video about how to run Alexa routines when you trigger your commands here:
https://www.youtube.com/watch?v=nrqj-OwDpGE
Also I forgot to ask, does it work if you run the command manually from a cmd window?