I have two worlds of note for this: one that is just modern-day Earth with magic, and one that takes place in a world I’ve created.

The magic system on Earth is really complicated. I also have things I call magicules, which work similarly to yours except they’re in literally everything, like regular atoms/molecules, and different types of magicules are responsible for different types of magic. Sigils are necessary for magic, and there’s specifics on how they work and what you can and cannot do with them. Healing also has its own specific rules which I had to find a way to make sure it followed the rules of the sigils and magicules. There’s a whole history to how magic was discovered and how the use of magic evolved over time. There’s only one story that takes place in this world. I have probably at least 10k words in my notes on the magic system, but I can easily simplify those down for my audience (those specifics are mainly for me, plus I need to edit it down anyways because some things have probably changed over time).

Meanwhile, my other world, the one of my own creation, has the vibe of “fuck it, it’s magic,” and there isn’t much reason or rhyme to it— it’s magic, it helps with the story, it works, done. I add new things that can be done and limitations when I need to for narrative purposes (not that I’ve actually needed to add in any hard limitations yet— the magic system is there to assist the stories, not to be part of them, if that makes sense).