Yes, United Airlines offers a 24-hour risk-free cancellation policy for flights that are booked at least seven days before departure. To receive a full refund, you must cancel within 24 hours of booking and cancel all flights for all passengers on the reservation. Partial cancellations are not eligible. https://support.skyvia.com/portal/en/community/topic/1-888-829-1467-does-united-have-a-24-hour-cancellation-policy-%E3%80%90direct-cancellation%E3%80%91