In a way, but the details are complicated enough that I'm a little fuzzy on how it all plays out myself. As I understand it though lemmy.world users would be looking at the version of the beehaw community that is stored on lemmy.world. They can view and even interact with posts and communities as if nothing had changed. However, any content they generate would not leave lemmy.world. Additionally there are details regarding how certain communities start being hosted that I am unsure of.