I don't know of any way to control the setting automatically (sometimes there are special-permission non-standard/undocumented intents for settings though), but as a maybe-close-enough you can turn on grayscale color correction (in accessibility -> color & motion, in my phone) and add a quick-settings tile to toggle it.

I'm on a Pixel 10 for these instructions, not sure if other manufacturers offer the same options.

Modes is an available option in the tile list. You can go to Modes, create a custom mode, and under display options you can set greyscale. You can also set modes to turn on automatically based on calendar events or a schedule. Notification tweaks are also available in the same area.

You can also use one of the accessibility shortcuts to trigger it quickly (both volume buttons held, triple tap, two fingers from bottom) if so configured