* Expository writing aims to inform, explain, describe, or define a topic. It's factual and objective, relying on evidence and analysis. Think textbooks, essays, news articles.
* Fiction is invented or imagined narrative. It may explore themes, characters, and settings, but its primary purpose isn't to convey factual information. Novels, short stories, and plays are examples.
While you might find elements of exposition *within* fiction (a character explaining something, a scene setting the background), the core of fiction is storytelling, not exposition. Trying to combine them in a pure sense would create a disjointed and likely ineffective piece of writing. A fictional work that heavily prioritizes exposition over narrative could feel more like a lecture than a story.
Therefore, "expository fiction" is a contradictory term. It's possible someone might use it informally to describe a fictional work that heavily relies on infodumps or lengthy explanations, but it's not a recognized literary genre.