It looks like a long sleeved tunic with square collar. The collar pattern was drafted by the cosplayer (or whomever made it), and attached to the top. There is probably a zipper somewhere, most likely down the back seam.
The collar will need heavy duty interfacing, or heavy lining fabric (twill or coutil) for it to maintain the shape.
As for patterns, look for tunic tops with a long sleeve and back zipper. You may also be able to use a dress pattern, with modifications to the bottom hem (shorten and add small side slits).
I'm assuming she painted the patterns pieces after they were cut out. Use fabric paint, or acrylic paint mixed with fabric medium.
The hat might be fabric covered cardboard/card stock or buckram.
Hope this gives you ideas. Good luck!