There are a number of discussions about the lack of URL scheme support here and here. And there are some examples of using iOS workflows (now known as Shortcuts) here.
It’s worse than not officially document; it’s not implement as near as I can tell.
If you try to create an iOS Shortcut you will see that Airtable is not listed as an app you can call in a shortcut workflow. I believe this is because Airtable has not registered a URL scheme with the operating system - ergo, URL schemes are not currently implemented.