I haven’t used these things except as they show up in results of a search; but if you tell it to write an essay on a particular issue, does it give references to the material it consults, or can you ask it to do?
Some do. They are all developing so fast that it is hard to keep up with all that they do. And they are all different.
Yes, they will give detailed references and citations especially if you request it. Some things considered “general knowledge” don’t get links but research almost always will.