Im using Auth0's universal login with Facebook and Twitter. By default both of the social networks return tiny version of the user's profile image.
With Facebook you can set a rule in Auth0 which returns the larger one, however I cant any way to do the same with Twitter (default is 48px).
I don't know if this is best practice or not but if you replace the string "A_normal" with "A_400x400" then you get an image 400px square:
picture.replace('A_normal', 'A_400x400');