Is there a way to filter out all link posts?

Your can add filters to ignore tags. Most links will have a source tag. Så add source to filtered tags in your sidebar will hide probably almost all link posts.

This bit of CSS should also filter out any links that haven't been tagged yet. Since it's a client-side tweak though, it'll mean an inconsistent number of results are returned per-page. It can be applied via extensions like Stylus.

.topic-listing li:has(.topic-title > a[href^="http"]) {
	display: none;
}