ZEROYAAMen's Urban Stylish Casual Business Slim Fit Long Sleeve Button Up Dress Shirt with Pocket

What is the neck size in a XL?

Is the shirt see-through?

I usually get my son 15 1/2.... 32/33 size in stores. There are no neck sizes, so which would be the correct size (Small or Medium)?

For neck size of 19, what size (XXL?) is required?