Peony's outfit doesn't fit his stature as the emperor at all. Starting from the top, Peony wears his hair down and while it's not all that long it still is a bit untamed for a ruler who is supposed to look dignified. He has a bead in his hair that is the same color as his eyes. Some fans speculate that it proves his status as royalty however there is no official explanation. Moving down you can see that Peony has well tanned skin. Which on one hand is surprising because he grew up in a snow covered village that rarely saw the sun but his home is in the summery looking capital. You can see his tan though his two shirts. The first is a plain black three-quarter sleeve undershirt while the second is a white or off white shirt with gold designs on the edges.

As for his bottoms he wears pants that make him look even more ridiculous.

Many wonder how or why Jade or his other close friends/allies/generals/etc. allow him to get away with looking ridiculous on a daily basis but really I think his crazy outfit is just what makes Peony their emperor. Aside from that the clothes wouldn't fit his personality if they weren't ridiculous. Or maybe, the rappigs ate all his good clothes.