I switched to using org-babel to manage my emacs config and it’s been helpful to keep things organized (and half-documented when I come back to it months later).
This is the best method I've found for managing emacs config complexity. I have thousands of lines of configuration in a single file, but the whole structure feels "not that big" because it is all organized into a logical hierarchy, with the gritty details hidden a few layers down, yet easily navigable with ordinary search features.
David Wilson has a good YouTube on the topic: https://www.youtube.com/watch?v=kkqVTDbfYp4