Can I illustrate a journal post using older observations?

that comment was in the context of the observation selection box on the journal page, as described in more detail here: https://forum.inaturalist.org/t/better-integration-of-observations-and-journal-posts/1267/8.

if you’re just looking for observations outside of that context, then of course you can search however you like on the Explore page or any other method you choose.