I've no problem with using LibreOffice for most of my document needs, but i haven't found a good substitute for microsoft's OneNote yet. I mainly use it to plan my RPG games and it helps a lot. What alternatives are there for organizing notes on linux, with similar features to those that OneNote provides?
Probably logseq or Obsidian, but… if you like plain text and really need customization you might go with what I use: emacs + org-roam
https://orgroam.com
Guides
text: https://jethrokuan.github.io/org-roam-guide/
video:
Start Using Org-roam Today | Install, Configure, and Use https://piped.video/watch?v=AyhPmypHDEw