No. Any extra charges at the airport apply in respect of extra services we provide to you in relation to your journey, e.g. checking you in or carrying extra baggage, in line with Ryanair’s General Terms & Conditions of Carriage which you agree to at the time of booking. You may avoid these charges if you check in online and adhere to the baggage allowances and size limits which you purchased at the time of booking your flight ticket.
If you think you have been unfairly charged, you can submit a complaint here.