If you want to see full size picture Instagram on a computer, then follow these steps:-
1. Open the browser on your computer.
2. Now visit the Instagram login page and log in to your Instagram account.
3. Now go to the user profile and open the image that you want to see in full size.
4. Now type media/size=l at the end of the address bar of the browser.
5. Then finally press enter and you will be able to see that Instagram image in full size.