As far as i know cookies can't be shared but there are some Apps that do something like that. I've been searching for several days but i could not find how they do it. For example, as you can see on image Like4like App opens a new window where the user logs in and then the App has Like permission of the user IG account.
There are many apps that can also do Follow/Unfollow.
what is the way to do that or keywords to search for the solution!? Thanks