If this sounds like your week
Your monitor already speaks a control protocol. Windows just won't use it for you.
Modern displays expose DDC/CI — a command channel carried over the same HDMI, DisplayPort, or USB-C cable as the picture. It's how the bezel buttons set brightness, contrast, and input internally, and it can be driven from software. Yet Windows ships no first-class way to send those VCP commands yourself.
Where tooling usually breaks
The raw alternative is fragile and unforgiving.
Hand-rolled scripts and legacy utilities fire VCP codes with no pacing, and the bus is delicate: too many writes too fast, or two senders at once, and you get flicker, dropped updates, or a controller that locks up until you power-cycle the panel.