You can, yep. You can skidaddle over to kbin.social and give it a go.
The important thing to remember is that all of the stuff that you do with your account (subscribing, posting, commenting etc.) is actually done by the server your account is on. The way you "interact" with users/content on other servers is that once you've "done something" on your server, it then let's other servers know about it (via federation).
So if you're a Lemmy user and say "I want to subscribe to tech@kbin.social", your Lemmy server will go away and pull down all the info for that community from kbin.social and start displaying it in your feed. If you create a post on that community, your Lemmy server will send a message to kbin.social containing all the info it needs to create the post.
Lemmy and kbin fully federate together, so all this works just the same as kbin-to-kbin or Lemmy-to-Lemmy. As also mentioned, kbin also has "microblogging" (Twitter-like posting) as well as Reddit-like thread posting, and fully federates with Mastodon in the same way.