TAbout the only credit a young adult can get is a ridiculously high interest rate credit card. In fact, you can probably get 20 of them if you want. I know I had $10,000 in credit at 19 years old with NO JOB. America, where credit is given to those who can't afford it.
A more standard way to start credit building for youngsters is with the purchase of a car. You are much more likely to pay this one as they can take your car away if you don't, and you only get that credit once, as it isn't revolving like credit cards you can use to buy just about anything now like booze, order Phentermine online, and play poker.
Here is an article about how to do it, and advice on how to do it right.