There are a few

I’ve been playing with LemmySchedule to schedule out posts ahead of time. This can be good if you want to sit down once and queue a number of posts to go out over the course of a few hours, or if you want to make recurring discussion threads (which work great for building up a community slowly)

There is also @bot@rss.ponder.cat, which you can set up to post from RSS feeds. This sounds closest to what you want to do from the other thread. The instructions are here: rss.ponder.cat/post/34622

There may be others out there :)