You can through kbin! There’s a nice discussion of it here.
You can add their name to your kbin url like this: https://kbin.social/d/social.bbc. It should open the page as if it were a kbin magazine and have a subscribe button. After that, you should see it when you browse your subscribed threads (although it seems like it won’t appear in your list of magazines).
I’ve seen a lot of lag and downtime from lemmy.world off and on. It seems like they get hit with DDoS or have maintenance issues (for lack of any real IT knowledge). I get the feeling they’re getting squeezed and targeted because they’re the flagship instance, but that’s just speculation on my part.
(Posting from kbin.social in case that matters.)