Starting chapters with epigraphs suggests that there’s something else with which the text is in conversation. (In historical fiction, this could be real historical sources; in scientific works, it could be earlier theories; in parody, it could be quotes from the target.)

In worldbuilding, you could use real-world quotes to imply that your world is in conversation with the actual world; or you could use quotes from fictional in-world sources to imply that your text is part of a larger in-world literary context. But in either case, it draws attention to the idea that the text is constructed, which may or not be what you’re going for.