Just be aware that in the fediverse everyone sees what you up and down vote.

As long as you have nsfw content enabled and your instance is federated with it (you'll have to check since some instances do not federate with porn lemmys due to legal concerns). The list of federated and blocked instances for your instance is listed in the "Instances" link in the footer of your instance.

If you find that you are indeed federated with it, you can subscribe to its comms simply by finding them in the search feature on your own instance. They will then be visible on your homepage when you sort by "subscribed".

You can simply open an incognito browser and go to pornlemmy.com

That site is just a normal lemmy instance, it just has a custom design. You can still sub to the communities from their on your current account, or you can make a porn alt on that instance.

On desktop, logged into whatever instance on which you have an account, select "All" (instead of local) on the main page. This will enable you to see all communities on all instances. Click the subscribe button on the right to subsribe to a community. Note that the community doesn't have to live on your home server for you to subscribe. Federation makes it so that different instances can share information with each other. Not sureif theresyet a wayto do the above on any of the lemmy phone apps.

Edit: instance as in lemmy instance as in website. For example my home instance is reddthat.com.