Search can be a bit iffy. It can only find stuff your local instance has indexed in its database, which is usually quite a lot. But it can have blind spots.

I haven't used jerboa in a while, but apps like Thunder let you define whether you want to search communities, users, posts, etc.

There is also lemmyverse.net which tries to index all instances so you can search the entire lemmyverse.

The search in Jerboa is...limited. It searches on community name(not display name) and it will only show about a dozen of the largest communities as results and nothing more. You essentially need to already know what you're looking for to find a great deal of value from it.

You really have to search for communities externally if you're looking for something that isn't a niche interest. There's a small handful of directory sites that help with this, but I can't for the life of me remember them at the moment if someone can help me out 😅

Edit: Mentaledge beat me too it. Lemmyverse.net is the largest of them.

I'm using Voyager and the search function is awesome. I stopped using Jerboa a long time ago and I don't remember exactly why.