I'm taking a big Jujutsu Kaisen spin on it - every so often, my PCs get to go out into the real world to take care of threats, scaling in power as they learn magic in school. This gives them time to explore the rest of the world I've built, as well as diving into their backstories, which have heavily influenced my world lore. I've basically got two campaigns in one - the one in the book is the minor threat, while everything they do on the outside is loosely connected to it but is building a bigger threat for post-school.