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?
You can't see it from your instance because not every community will be pulled. A community only starts federating to your instance after someone on your instance subscribes to it
Lemmy isn't focused on everyone seeing everything but on keeping corporate interests and power tripping admins out. The idea is to encourage as many people as possible to run their own instance of Lemmy both to share the infrastructure costs and limit the power each instance holds. Keeping hosting costs down is why instances don't pull from communities nobody is subscribed to.
If not, someone could just set up a rogue instance, create fake communities on it, then start pushing a million pictures per minute to every Lemmy instance, exhausting their resources
Tesseract lets you browse the communities on remote instance. AFAIK, that's one of few Lemmy frontends that offer that feature. Wish some other frontends would steal that feature from me.
Since the requests it uses to fetch communities from the remote instances are unauthenticated, it won't show you any that are marked NSFW.
I will add to others' comments, that although this is the default on the communities list, make sure the "Local" option is selected to see all communities on the specific instance or "All" to see all communities the instance federates with (in other words, all the communities it allows access to)