Air Carrier Access Amendments Act of 2021 This bill expands provisions prohibiting discrimination against disabled individuals by an air carrier. Specifically, it enumerates certain actions that an air carrier must take or may not take with respect to a disabled individual. It also requires the Department of Transportation (DOT) to ensure that disabled individuals traveling in air transportation are able to file complaints with DOT in response to disability-related discrimination and receive assistance from DOT through a hotline or comparable electronic means. The bill authorizes an aggrieved individual and the Department of Justice to bring a civil action for discrimination. The Architectural and Transportation Barriers Compliance Board shall prescribe regulations setting forth minimum standards for aircraft with new or existing type certificates to ensure the accessibility of individuals with disabilities, including those who use wheelchairs. The standards shall address, among other things, boarding and deplaning equipment, seating accommodations, lavatories, visually accessible announcements, and proper stowage of assistive devices in the cargo hold to prevent damage.