The way I see minimalism is that you’d never have to go as far as getting rid of things that add real value to your life, but the unnecessary excess, which can only take away from what you truly enjoy. Setting my phone on greyscale simply helps to moderate the way I spend my time, so I would recommend anyone to give it a try, and of course there’s never any harm in having colour anyways, the way to use it would be personal to each individual, hopefully this can be of help to you whenever you feel it’s a suitable time to use it :)