Help me adjust this pattern

I am looking for a simple warm hat for my 3 year old DD. Her head circumference is 19 inches. Is this an appropriate pattern for her head size? If not, can you point me to another pattern with the same gauge? I have done multiple searches but can find a simply kid’s hat that is knit in the round with a guage of 5 stitches per inch.

I think that would work for you daughter, but the only way to be absolutely positive is to knit it. If you are using a different worsted weight yarn it could be a slightly different gauge or your knitting could be tight or loose.

It’s just worsted weight yarn and there are lots of patterns for worsted weight. To adjust it all you’d need to do is change it in multiples of 4. The original cast on is 64 so to make it slightly smaller you could go down 4 to 60 or if you need it bigger go up to 68, etc. The only other change would be to the decrease rows at the top and we can help with that when you get to it.

That hat is supposed to be 12 inches around for a preemie baby. You will want a hat about 17 inches at least to be snug but not too small. At 20 stitches makes 4 inches you would want about 85 stitches. You could use that pattern stitch for the ribbing but cast on 84 stitches. Work rows 1-7 as given but do the repeats 21 times instead of 16. Then work for about 4 inches in st st before beginning the decreases.

Crown (this gives you 7 decreases on each decrease round)
Row 1: K12, PM around.
Row 2: K to 2 before marker, K2tog repeat from * to * around.
Row 3: K even (the pattern says to knit 2 rows even between each decrease round, you could, or just k one round or sometimes 1 sometimes 2 to get a desirable shape)
Next rows: repeat row 2 followed by however many even rows you want between the decrease rows. Keep repeating until you have worked to where you have only the results of K2tog all the way around. Cut the yarn and run a tail though the live stitches. Weave in ends.