Example photo : https://www.instagram.com/p/BvkCr95FcGG/ i want to get url image large.
it simple.
use parameter after the url image media/?size=l
Thumbnail ?size=t
Medium ?size=m
Large ?size=l
example https://www.instagram.com/p/BvkCr95FcGG/media/?size=l
;
hopefully it can help you.