Do airlines have to pay for Cancelled flights?

In the United States, airlines are not required to compensate passengers when flights are delayed or cancelled. Compensation is required by U.S. law only when certain passengers are “bumped” from a flight that is oversold. 01-Sept-2022

https://www.transportation.gov/individuals/aviation-consumer-protection/flight-delays-cancellations#:~:text=In%20the%20United%20States%2C%20airlines,a%20flight%20that%20is%20oversold.