Controling the colour of the lights on the Novation Launch Control XL requires that you send midi data to it.
That's what a Control Surface plugin (csurf plugin as Reaper calls it) usually does.
We do not yet have automatic midi feedback to indicate for example the state of a setting in Reaper as a colour on that button. Setting up such a relationship may be possible with Geoff Waddingtons project in this thread:
https://forum.cockos.com/showthread.php?t=183143 .
You can write a Lua script that sits in the background, checks certain states periodically, and sends midi commands to the Launch Control. Help for doing that is readily available in
this forum section.
I've written some small scripts that just change some lights on an X-Touch Mini, as I use it to choose banks on another controller. It's not very hard once you get used to Lua. Lots of folks will help you as well.