Unlike many of the games on this list, Paladins' holiday content is relatively meager. But it's the holiday season and developers seem to feel obligated to make holiday content for their persistent world games. So let's see what we've got.
First, each day from December 19 to December 26 will have a different chest on sale. Sadly, the devs are keeping the "chest of the day" a secret until the day it's actually available and the page where its supposed to be updated hasn't been done in a timely manner. With that being said, I'd suggest just checking out the in-game store.
Paladins is also having a so-called "Holiday Calendar". Each day on their official Twitter account they will post a new link to a new trivia question. Answering the trivia question properly will enter you into a raffle to be one of a handful of people that can earn that particular day's reward.