At some point during the concept stages, old equestria was apparently considered a viking world as told by history. Celia Kaspar has revealed what Twilight and Applejack would look like that with that aesthetic. Have a quote:
Sooo in viking earth pony world (in a world long looong before Sunny and her friends) this would have been an idea for Twilight and Applejack!✨ They look pretty different here, don't they? Would you have been able to recognize them? 😊
Thanks to Pipp_Petal for the heads up.