I got my chest x ray results and it says hyper expanded lungs probably due to emphysema. what is the best test to rule out copd?

You would need a pulmonary function test. In COPD, it would show obstruction that does not significantly improve after a bronchodilator is given. If it does not show obstruction, then there is no COPD. If it does show obstruction that improves w/bronchodilator, it is more likely asthma. If you smoke, you need to quit ASAP. See a lung doctor. Best of luck to you!