I develop a HN/Reddit clone [0] that has high density settings. The home page is fairly high density by default. But if you go into the settings [1], then you can really crank up the home page UI density by setting posts per page to 50 and post spacing to 2. The density is more apparent on desktop since the lines don't wrap.

[0] https://www.commentcastles.org

[1] https://www.commentcastles.org/settings