<?php

function getProfilePic($username)
{
    $data = file_get_contents('https://www.instagram.com/' . $username);
    $data = explode('window._sharedData = ', $data);
    $data = explode(';</script>', $data[1]);
    $data = json_decode($data[0], true);
    return $data['entry_data']['ProfilePage'][0]['user']['profile_pic_url_hd'];
}

echo getProfilePic('user');

?>