I made the size 10 for my tall 8 yo daughter, it fits as a tunic, almost a short dress. I alternated strands of madelinetosh sock with a specked yarn to make up a fabric of her favorite colors. I knit the first 20cm or so on sz5 needles to give it a bit more of an A line, then knit the rest to gauge.
The neckline was a bit tricky for me, maybe because I knit at night! I ended up needing to rip back the bands, though I did like how they looked. Zoe doesn’t like anything too close fitting around her neck. I picked up the stitches as the pattern suggested, but just added two additional pickups at each shoulder and knit it all in the round. Now it fits as she likes, and will get loads of use.