You would need to contact Copa to see about any costs or compensation. I doubt there would be compensation, as I believe they indicate on their site that the aircraft type can be changed. Switching to IAD provides 3 flight options. However, the two early flights in the day also have the 738 scheduled. The last flight of the day, CM444, has the Max9 scheduled and for the past week no aircraft type change is shown in Flightradar24.