Those who pre-ordered the Kingdom Hearts III Deluxe Edition have received, along with an exclusive steelbook and pin, a copy of the game's artbook. This starts with a message director Tetsuya Nomura wrote for the readers and includes character renders, screenshots, and concept art of bosses, Heartless, Gummi Ship enemies, Keyblades, and other weapons including Attractions. It also has an indicative timeline of the games in the series, although it seems to include some inconsistencies (Chain of Memories placed further ahead of Kingdom Hearts and right before Kingdom Hearts II, and "Kairi rescued" instead of "Namine rescued" in the middle of Chain of Memories.)
Notably, the book includes the screenshot of Marluxia from the older trailer footage rather that from the game, as he seems to have blue eyes. The design choice of the Large Body heartless is also interesting; this is the design it takes in Arendelle. However, the clothes don't match any traditional styles in Norwegian or Scandinavian folk culture, but is slightly reminiscent to the style of clothing of the Sámi people, who inhabit huge parts of Northern Scandinavia. This style of clothing is also the same that Kristoff has during most of the original film.
For those who couldn't obtain the artbook, luckily we have procured scans that you can view in the album below! The scans are courtesy of KH13 Staff HaakonHawk.