Having multiple cameras and setting grayscale during runtime with script

Hey all, I have a question. So I am in the processing of starting to make a game and I had this cool idea involving colors but am not too sure how I would achieve it. Essentially I want to have lots of different cameras, each affecting a different layer setting it to grayscale. The user would then complete actions that would trigger certain layers with their corresponding cameras turning the grayscale off returning that camera back to its normal state. How can I achieve this through the use of a script, like it is it possible for me to be changing that during runtime and how?

 

You should look into postprocessing stack and image effects about those greyscale effects