Eva Air Cancellation policy says if you want to get a full refund on Eva Air, you must cancel your flight tickets within 24 hours of booking the flight. This way, you do not have to pay any cancellation charges.
Also, airline tickets made seven or more days before departure can only avail the benefits of Eva Air's 24 hour cancellation policy.

https://www.cancellation-policy.com/eva-air-cancellation-policy