Yes, you can add Priority & 2 Cabin Bags to your Ryanair booking at any time up to 2 hours before your flight via the Ryanair app or website. However, in 2026, there is a catch: Priority is limited to about 90–100 passengers per flight to ensure there is enough overhead locker space. If you wait too long and other passengers have already purchased the allocation, the option will be "greyed out," and you will be forced to buy a 10kg Check-in Bag instead. Buying it later is also typically more expensive—while it might cost £6–£12 at the time of booking, adding it post-booking can cost up to £20–£30. If you know you need that extra carry-on bag, it is highly recommended to secure it as early as possible to avoid the "sold out" status and the higher "post-booking" service fees.