Thanks for sharing the screenshot. What you've shared is the Additional scripts feature for the order status page. There is no missing feature from your screenshot, this is how you can add scripts and other customizations to the order status page!
Note that this is an advanced tutorial that is not supported by Shopify. If you're not comfortable following this, I recommend hiring a Shopify Expert. Or perhaps another Community user will be able to assist.
Hope this helps!
Hilary | Community Moderator @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog