I’m using voyager and can long press the community name when browsing to bring up some options, I can block out subscribe right there. Does yours do that?

The API allows blocking communities without ever interacting with them. It's just the limitation of the client you use.

https://join-lemmy.org/api/main#tag/Community/operation/BlockCommunity

I'm using Connect and there's the 3 vertical dot menu on the post itself that brings up a menu that has an option to block the community. Very handy. I use it a lot to block more extreme NFSW stuff just randomly shows up.

No, you can also go into your settings and add it to the blocklist there.

I went to block it and was suprised to find I can’t not see incest without going into the incest community to ‘block community.’

While going to the community and hitting the "block community" button is one way, its not the only way. For your desire to not enter the community, in the web browser, you can go into your settings and block from there:

Here's mine for example, go to your settings:

Select the Blocks tab:

You will find a "search" box there you can type in the Lemmy community name. Even a partial typing will return results and give you a list to choose from:

With this method you never have to enter the community to block it from your view.

Just a heads up, I don't think there's a "default" Lemmy viewer. Each instance set up its own viewer, and also clients can have their own as well. This doesn't answer your question, but it is important to note, because some answers may not apply for whatever viewer you're using if you don't know what it is.

There should be a 'block' button as well as a 'subscribe' button at https://lemmy.ml/communities

piefed allows you to block from the feed. Its a hit and miss difference. For example in mbin going to a community showed if it was blocked but piefed I have to go to my block list to see. granted its kinda obvious as there is not posts showing up but I hate not having the obvious showing its state. Now that you mention it though I was sort frustrated with that but blocking from main feed is actually pretty great I guess.