I've just installed a plugin in my emacs config the other day called dumb-jump[0]. The way it works is by running a grep tool (grep, git-grep, the_silver_search (ag), ripgrep) inside the current project with some patterns according to the file type. It hooks into emacs xref (dynamic links and history).

These days, I'm using very minimal highlighting (doric-themes [1] which is basically shade of one color and font-weight). I prefer to separate semantic units of code by whitespace. Then scanning becomes quick.

[0]: https://melpa.org/#/dumb-jump

[1]: https://elpa.gnu.org/packages/doric-themes.html