This headband pattern is available in two child sizes from three to five years of age. With that said, I think you can crochet this to any length that you like.
And as far as I can tell, the pattern does not include the pretty flower, but you might be able to find it on the site somewhere.
You will need a 3mm crochet hook and a yarn to go with it.
If you enjoyed this free crochet pattern you might also enjoy more designs by Crochet/Crosia Home.