I think ( never used it ) that although world composition is often used for landscapes, it’s also a general method of dividing a large world into chunks ( held in maps ) which are loaded in realtime. You also have the rebasing.
With level streaming volumes, it’s loading in realtime, but I don’t think it deals with the origin problem. If you did it with level streaming it would need to be blueprint based and all levels would be loaded at the origin. You could use the tunnels as an excuse to stream.