You might have to hit /latest.json?page=2 instead of /posts.json and filter out the posts from the result.
https://meta.discourse.org/latest.json?page=2
EDIT: Ohh you want latest posts, not latest topics. Considering /posts by itself doesn’t have a UI, it probably is missing pagination, I’m sure a PR could be created for this. But to get what you want right now you could still parse the /latest.json endpoint and parse out the topic_id and the post number and fetch the post with /t/<topic_id>/<post_number>, but yea I can see why pagination on the /posts endpoint would be helpful.