u/Serpenta4

I’m thinking of making this for my 4 year old niece. The pattern says to use a bulky yarn with a 5.5 mm hook. With the yarn they recommend a 7 mm hook, but I assume it can be used with a smaller hook, because it’s fluffy. Is that a good assumption? Is the pattern even possible with this kind of yarn? Also, the pattern says that it needs 200g or 320y of yarn for a child size, do I then buy 5 balls of yarn to be safe, or maybe 6?