Comment by WorldMaker

The proposers of `light-dark()` themselves recognized that `light-dark()` was presumably a "stepping stone" towards (and then eventually just a shorthand for) a deeper `schemed-value()` function similar to what you are asking for, once CSS also picked up a way to define custom color schemes. (Often proposed as an `@color-scheme` rule or block.)

It can be an interesting discussion to follow: https://github.com/w3c/csswg-drafts/issues/9660