Hey ll17ll,
I know you're just starting out, but going from 0-60 is hard enough, and wondering if you'll get holidays off should be your least worries. But, to answer your question, for the most part, junior pilots, regardless of cargo or passenger, or smaller entry level airlines, or majors, the odds are you will have to work over holidays at least your first couple of years. If you're young, and have the means, you're getting in at a great time right now. Good luck with your flight training, and have FUN!