Mentioned in a blog post and resource list at https://booksbeyondbinaries.blog/2019/11/25/trans-affirming-picture-books-2019/

Riley selects a different outfit each day, depending upon their planned activities, and how they feel. A ball gown for dinner out at a fancy restaurant, outer spaces jammies for Universe Day at school - the clothing Riley wears is always suitable for what is going on at that time. When a kid at the park asks whether Riley is a boy or girl, the fashionable youngster avoids answering, replying: "Today I'm a firefighter. And a dancer. And a monster hunter. And a pilot. And a dinosaur." All ends well when the kid in question accepts these answers, and invites Riley to play...

Although I think its heart is in the right place, when it comes to promoting the idea that a child's dress does not have to be gendered in a particular way, regardless of that child's gender identity, What Riley Wore didn't particularly impress me, otherwise. The story itself was really just a list of outfits worn by the eponymous Riley, while the artwork, although colorful, felt flat and unappealing to me. Afsaneh Moradian did something similar to this in Jamie Is Jamie: A Book About Being Yourself and Playing Your Way (although her book focused on gendered play rather than dress), and I found that title more appealing, somehow. Tastes vary, of course, so I'd still recommend this one to those seeking picture-books about non-binary and/or gender fluid children. ( )