Although the directions are only for sizing to fit adults, you could use the same principal to make the belt for a child. Just reduce the number of inches added to the waist measurement and the number of flowers.
PS- this also makes a really cute scarf!

The belt is worked in rows, with flower motifs sewn on. In addition to yarn in your choice of four colors, you will also need a size H hook, a tapestry needle, and a 1” button.

I didn’t determine yardage. However, it is a minimal amount of yarn for all four colors. Two colors are only used to make to flowers. Color A is the main belt color, and color B is used in flowers and a surface crochet stripe. I used “Warm Brown,” “Coffee,” “Cafe Latte,” and “Buff.” This would also look lovely in brighter colors!

Stitches and terms used (US terminology):
st- stitch
slst- slip stitch
sc- single crochet
dc- double crochet
ch- chain
FO- finish off
RS- right side
WS- wrong side
chainless foundation sc