Yes, Frontier Airlines allows passengers to book seat assignments in advance. When booking a flight, passengers have the option to select their seats for an additional fee. This selection can be made during the initial booking process on the Frontier Airlines website. Additionally, if passengers choose not to pre-select their seats, they will generally be assigned seats at check-in, which is complimentary, but the specific seat location cannot be guaranteed. It is important to note that certain seats, such as those with extra legroom, may incur higher fees when selected in advance. For detailed information on seat assignments and associated costs, travelers should refer to the seat selection section on the Frontier Airlines website.