Ah, if you just want something other than the lemmy.world instance, but are okay with lemmy-the-server-software, you can get a list of other lemmy instances here:

https://lemmy.fediverse.observer/list

And since I mentioned the other instance types above, for mbin:

https://mbin.fediverse.observer/list

Kbin:

https://kbin.fediverse.observer/list

Piefed:

https://piefed.fediverse.observer/list

A couple of recommendations, if you want another instance. I don’t know what “broadening horizons” here deals with.

You can see what instances a given lemmy instance has defederated with at /instances. So for lemmy.world:

https://lemmy.world/instances

I can’t link there directly, unfortunately, but click on “Blocked Instances” and you’ll see a list.

• My own view is that lemmy.world is a pretty decent general-purpose instance.

• I use lemmy.today because they specifically have, as a policy, that they try not to defederate with other instances (which it sounds like is something that you care about), that they want to let the users choose want content to see. It’s on the West Coast, US, which may-or-may-not be near you. So if you’re on there, you can browse anything…but it doesn’t have a huge userbase, at least not yet, and an instance needs to have users that subscribe to new content before it shows up in an all feed. So you may want to hit https://lemmyverse.net/communities to find new communities to subscribe to, rather than just sitting in the “All” feed (which I don’t personally think is a great way to find new communities anyway, but…)

• beehaw.org is generally more restrictive than most instances, so it probably isn’t what you were after, but it defederated from lemmy.world some time back, so if you’re after their content, you might want an account there or an account on an instance that it has not defederated from. I’m not really enthusiastic about their moderation policy, but they do consistently have solid discussion, IMHO.

• lemmy.dbzer0.com is run by the ex- /r/piracy lead moderator on Reddit, and is aimed at piracy. Lemmy.world has not defederated, though I can imagine that some instances might, so if that’s what you’re after…

There are various special-purpose instances, like https://pawb.social/ for furries or https://mander.xyz/ for science, but I don’t think that these are likely to have most general-purpose instances defederate from them. So you probably don’t need another account off lemmy.world if those are what you’re after and you’re wanting more content than is accessible from lemmy.world.

Looking at lemmy.world’s defederation list, from a quick skim, the stuff there tends to fall into a few categories:

• Far-right stuff that doesn’t get along with others, like https://skinheads.social/

• Far-left stuff that doesn’t get along with others, like https://hexbear.net/ or https://lemmygrad.ml/

• Underage anime porn, which is illegal in some locales, like https://burggit.moe/ or https://headpat.cafe/ (pleroma, not lemmy). Burggit.moe, as I recall, also deals with consentual-nonconsentual content.

So if you’re looking for anything there, you can probably just grab one of said instances and get an account there, as I doubt that they’d defederate from other instances that deal with similar content (though I dunno, not familiar with any drama there…lot of fractious far-left groups in the world who don’t like other far-left groups).