If we meet Papyrus in game there is a chance he could have an outfit that looks like, or styled after a police uniform

If the personality of Papyrus is the same between Undertale and Deltarune and if he also looks up to Undyne the same way. Papyrus might have dreams of wanting to join the police force just like he wanted to join the royal guard. This is just my assumption that his battle body in undertale is what he wanted to wear if he was a royal guard.