FYI windows already has a monitor blue shade/color shift built in. Dimming external monitor outputs on a desktop is likely not possible.
You'll need to hook into the windows API somehow to control windows functions. There's some documentation about adjusting color temperature (making that warmer would essentially add a "blue light" filter to a screen on microsoft's website.
In terms of executing a small CPP script that actually can interface with windows, you can write a small CPP program, then compile it and execute from python using (slightly modified from this question)
import os
import subprocess
for filename in os.listdir(os.getcwd()):
proc = subprocess.Popen(["./prog", filename])
proc.wait()
However if you don't have the room to install visual studio compile tools, you won't be able to compile a small CPP script locally. There are a few online services that would be able to do that for you though.