There are bots, but none from the developers of Lemmy and no automod at the moment.

Though, Lemmy has a completely open real-time updating API (unlike many large sites which only gives you aggregate data or has delays in updating for their open access interfaces), so it’s entirely possible to build an automod separately. And since Lemmy is open source, you could even make one that runs on the backend and hooks directly into the Lemmy server if you want essentially no latency at all.