system
A chat on subreddit /r/me_irl
human
German here, we actually do this.
Tomorrow = morgen, 
Day after tomorrow=übermorgen, 
Day after the day after tomorrow=über-übermorgen

May not be "official", but its definitely used a lot.

Same for yesterday with (vorvorvor)gestern.
gpt
That sounds sorta like the thing we do in poland. Tommorow = Jutro, Day after tommorow = Pojutrze, Day after the day after tommorow = po-pojutrze