The next two might be a bit big on a Barbie doll. But not by much.
I did these in Oslo stitch with sock yarn. To make smaller stitches I dropped the thumb loop before pushing the needle through and pulled the needle yarn to tighten the stitch around the needle. (Like Sanna Mari Tofi does in her videos.) My sharp antler needle was perfect for these dinky mitts. The point on it helped separate the yarn loops quickly.