Is Sourcetrail and a document for taking notes measurably better than having an IDE with 2 panes, "go to definition" and "find all references", and a document for taking notes? In my experience it's not really, and it was tricky to setup Sourcetrail for a given project.

I saw in another comment saying Sourcetrail supplies "who-implements-who". CLion gives you this, Qt Creator doesn't really (outside of Find References), and I'm not sure about VS Code Clangd or Microsoft C++.