You are too late to file for an extension unless you are out of the country. You had to request an extension by April 15, 2019--and you had to pay by then. An extension does not give you extra time to pay. It only gives you extra time to get your documents organized and prepare your tax return. Now your return is just late. If you are getting a refund there is no penalty for being late. If you owe tax due, then your interest/penalty began after the filing deadline. Get your return filed as soon as you can.
https://ttlc.intuit.com/questions/2549773-can-i-file-an-extension-after-april-15-2019