Unfortunately, 10 years is the maximum any domain can be registered for, however as years are used up, you can add years to your domain registration as long as you do not exceed 10 years.

For an example, if you register your domain on June 15, 2023 for 10 years, your domain will expire on June 15, 2033. You cannot add any more time to the domain. After June 15, 2024, you can add, at most, 1 additional year to your domain at the current 1 year price. So if on June 17, 2024 you purchase 1 year renewal, your new expiration date will be June 15, 2034.

Domains with current 10 year registrations cannot be transferred unless there are 9 years or fewer until expiration. This is because transferring a domain will add 1 year to the expiration. You must wait at least 1 full calendar year to transfer otherwise the transfer will be rejected by the registry.

Any time you choose to add years, you will do so at the current price. So if you register a domain for 2 years at $12, you will pay $24 today. If you decide to add another 2 years later but the price is now $14, you will pay $28.