Square Enix updated the official site for Final Fantasy XVI to include the Eikons’ art and details. They are under the Characters tab. It also added more information about the battle system under the Battle page, and you can also view all the new videos or pictures under the Movies & Images tab.
The Eikons do not have their own section on the Characters page. Instead, they are a tab that you can toggle through on their respective Dominant’s profile. Though it shows a picture of each of the Eikons as they appear in Final Fantasy XVI, it does not give much of a description on who they are. For example, Jill’s profile states that she is the Dominant of Shiva and you can pull up a picture of Shiva, but that’s it.
In previous Final Fantasy titles, Eikons and their equivalents are more plot devices and tools in battle than actual characters. This might explain why Square Enix did not provide them with much flavor text. For those who wish to see the full-body art of the Eikons, you can do so on the Movies & Images page. You will have to click on the plus sign in order to expand the page enough to see them.
Final Fantasy XVI is in development for the PS5 and it will come out on June 22, 2023. There will be a six-month exclusivity period.