I use emacs, and it can change font size and font face similar to the font color during syntax highlights. Like in markdown or LaTeX headings are larger font, math formula have their system where superscript and subscript have higher/lower baseline. In org mode it can even convert the whole latex snippet into formula and display as image, or show inline images. And in rust it has type hints and other information overlayed along side the code you wrote, it even adds little buttons on tests you can click to run them.

So I think what you want can probably be made easily if you have a solid grasp of what you want. Emacs is basically extensible using a programming language (elisp) so technically there's nothing you can't do logic wise, there might be some limitations on displaying things though.