Language code with more than 2 letters

Hi there
I was wondering if there is a way to have more than two letters for the language code (under localization)? For example in german there are some inguistical differences between countries (de (German), de-AT(Austria), de-CH (Switzerland), de-LI (Liechtenstein)).

Thanks for your help!

Any web-supported language code can be used in this setting. You can see all supported ones here: List of ISO 639-1 codes - Wikipedia

Also noted here: Set your site's language code | Webflow University.