The La belle dress is a made to measure and size inclusive design. This means you measure yourself and then follow the instructions, this means it can be made for any size and age.
The pattern is written in US terminology and is an advanced beginner level, it has detailed steps, stitch graph and photos throughout each step to help guide you.
You will need any type of 4ply (fingering weight) cotton yarn and a 3mm crochet hook, I used roughly 1600m of yarn for the sample size (small UK 8).