American Airlines flight change policy offers flexibility for passengers needing to modify their travel plans. Depending on the fare class, changes can be made for a fee or without charge, particularly for tickets under specific conditions. Passengers may need to pay any fare difference if the new flight is more expensive. Changes must generally be made within a set time before departure.
https://www.toursntravelpro.com/flight-change-policy/american-airlines-flight-change-policy/
What is the American Airlines Flight Change Policy for Basic Economy Tickets?