Hello,
It’s possible to make header sticky using CSS only with the top bar https://gyazo.com/a7a3b3572dc6560b3895a85af7967bc9 . If you want to make only the main header area + menu as sticky it requires the JS changes. In this case contact WPKraken team to implement this because such additional customization is not included in our support https://themeforest.net/page/item_support_policy
Regards