Instead of just searching the specific name of a sub what if I want to see every sub that’s contained within an instance such as lemmy.world for example no I’m not part of lemmy.world but as part of the instance I’m a part of I can see every sub under it in a neat list can you only do that if you’re part of the instance?
So, from what I can tell anyways, it does seem like the original answer is what you’re looking for. Each instance has a list of its own communities that you can see. You can also see a list of other instances that are federated to an instance by browsing to /instances (ex. https://lemmy.ca/instances shows all the instances lemmy.ca is federated with as well as which ones are blocked). As far as I know, there is no way to see a list of all communities from all federated instances. There are some external sites that seem to have these sorts of lists like https://lemmyverse.net/communities