Disney Mickey Mouse Baseball Hat, Washed Twill Cotton Adjustable Dad Cap

Is this for small children or adults ? I can see it’s adjustable but for anyone who has purchased , would this fit a 4 year old?

We're going to wdw next month where it'll be super hot. does the khaki color or any light colors show sweat stains? is the hat breathable?

What are the dimensions or measurements of the hat?