In this category I would nominate Django as well. It's very well designed (opinionated, but usually for good reasons).

In terms of large C code bases I enjoy reading the PostgreSQL source code.

whenever I'm stuck on how to structure some code, I ask myself how would Laravel do it? and look up their code and structure mine similarly

My story is similar, but using Laravel as the canonical example of how not to structure things. Even without Facades, the internals are an impenetrable maze of magic methods, with things like Macroable adding methods from dog-knows-where. Even adding phpdoc types doesn’t work when dealing with things like scopes.