I have yellow and deep orange filters for my lenses, I'd like to try dark red at some point (probably going to see very limited use, as deep orange already gives quite dramatic sky and clouds).
To me it is part of the beauty of a rangefinder system that the view is not affected when mounting filters (for black and white).
The one thing I suggest to ponder, and make up one's own mind about, is to whether one really (and for what aesthetic purpose) wants (leaving skin tones aside, and talking about the sky/clouds) the clouds to "pop" and the sky to be a bit darkened as compared to unfiltered rendering.
I mean this in the following sense: some filtering or exposure strategies are things one may pick up when setting out with photography, because one reads about it a lot, and because it sounds like you miss out on something if you do not do it. Best example for me would be "shadow detail" (and the recommendation of downrating film). It is good to know about that, one should try it, and be able to use it as a workflow or tool.... because one wants to, and because it fits your visual style. It can be perfectly fine though to let the shadows go dark or all black 🙂
With filter use for making clouds stand out, I feel it is in a similar way. I have a number of pictures where I am really happy I had filters handy. And yet I know a number of "landscape" pictures in black and white that "work" precisely because the sky (and clouds) do not stand out, do not have texture, but are just plain bright and white. It became most clear to me when seeing a late "landscape" picture of Cartier-Bresson, where the geometrical - if you will - beauty works because the sky is one continuous tone, and the eye is not distracted by counting clouds ;-)
So, I always have filters in my bag, and when the light is not too contrasty already I keep a yellow filter on the lens. And at some point I'll even buy a green filter, for the very rare occasion that a portrait could work with very pronounced skin tones.
Greetings, Ljós