No, it doesn't. It wants the team to discuss features to help find preventable issues up front and to make it as clear as possible. The unknown unknowns remain unknown, which is why an estimate is an estimate, and a sprint is a best-effort attempt at getting a thing done. If and when it becomes clear that this feature is too complex, too big, or whatever, then it can be reestimated, or decomposed or reevaluated. It's supposed to be agile, not rigid and fragile.