Nowadays, I would start with an outline if I was asked to write an essay, but that’s because I have enough reading, writing and life experience that I would have a guess at what that essay would look like.
I just imagined sitting down to write a novel (which I’m actually trying to do right now) and that totally wouldn’t work with an outline. I only have a vague idea what the main themes are but I don’t know the story until I explore it with my characters.