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). For example, I'm testing it out with another account here: @otters_raft@lemmy.ca
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: https://rss.ponder.cat/post/34622. For example, I have it set up to post from a youtube channel in !marinemammalrescue@lemmy.ca
There may be others out there :)