I have a few baby dress patterns in size 0-3 months and 3-6 months in my Etsy shop, and I've been getting a lot of requests for baby dress patterns for larger sizes.
Finally, here is a baby dress in size 12-18 months.
This dress is made with fine, category 2, cotton and acrylic blend yarn, and a hook size E/4 (3.5 mm).
The cotton and acrylic blend yarn gives a light texture, that is suitable for a summer dress.
I do believe the dress would look much prettier on a child, rather than on my mannequin.