Ah, I see what you mean now. In that case I don't think you can do it on Kbin natively rn. There is this website though, which might help a bit. At least imo it's easier to use. https://lemmyverse.net/communities
You can just filter for only lemmy.world. When you find a community you want to join you'll have to type the handle of the community in the search icon to the right rather than in the Magazine tab for communities that doesn't already have a copy on your instance.