What you want to use as a decoration is only up to you.
As for me, I usually use a bunch of items related to creature products that would fit the theme (such as a dragon claw in a dragon-themed home) as decorations.
In this case, items such as a celestial chart would fit perfectly in a magic-themed or even book-themed home, while a colorful water lily would fit in some water-themed home.
Though I can provide you with list of all items added in patch 12.90.1218
https://tibia.fandom.com/wiki/Updates/12.90.12182
I'm sure you'll find some more great items there!