Can't know for sure unless you try!
Are we using the same service? I've been scrolling my feed all day.
There's a "Show Read Posts" checkbox in settings. Is that not what you are looking for?
As far as I have noticed, if you've voted on the post that also counts as "read".
Sorry, I suppose, I used confusing terminology.
I mean, for instance, there are multiple, idk, Technology oriented communities. I just subscribe to all of them, or at least the ones with a significant amount of users. In time, a "main" one will probably emerge among them.
I had that with masto. Not so much with Lemmy. I just sub to all "clone" communities, especially meme ones.
Can't know for sure unless you try!