$f_json = '
https://www.instagram.com/it_cube/?__a=1';
$json = file_get_contents($f_json);
$obj = json_decode($json, true);
//var_dump(json_decode($json));
for ($i=0; $i<=11; $i++){
echo $i.' поcт'.'<br>';
echo $obj["graphql"]["user"]["edge_owner_to_timeline_media"]["edges"][$i]["node"]["edge_media_to_caption"]["edges"][0]["node"]["text"].'<br>';
}