Update: I found a page in fedi.tips that has a lot of detail on this: https://fedi.tips/which-posts-and-accounts-can-i-see-from-my-server/

Federation is a beautiful thing. However, I’ve known that smaller, newer servers’ content isn’t always seen on others and vice-versa. And that over time that improves and increases.

So, for example, NewAndQuirky.social starts up. If an account on day 2 of that server does a search on quirky-topic, from which servers would content be seen for that?

Would any contact (a follow, a boost of a post, etc.) between New&Q and another server open up all data from the other? Or just posts related to the boosted posts, or posts from followed accounts?

And just new, or new and old? Any other information on the logic/algorithms of server interaction data would be appreciated.