[Update]: Overwatch is heavily nerfing Sigma, Wrecking Ball and Ashe, while also buffing Hanzo.
The annual Winter Wonderland event has made its way to Overwatch a little while ago, bringing with it a whole assortment of goodies. There's a bunch of new cosmetics to unlock through either events or loot boxes, a variety of festive skins from previous events that you can grab at discounted prices, a very snowy reskin of King's Row, and even a brand new twist on the deathmatch mode.
If the cosmetics in particular are what tickles your fancy, you'll be extremely happy to hear that Blizzard has now sent out a bunch of free loot boxes to all players as a small gift for the holidays! In order to unlock your five free loot boxes you merely need to log into Overwatch before January 5, 2021. There's no catch or anything like that - simply log in and you'll be able to get a bunch of the new event items!
On a similar note, it's also worth mentioning that Overwatch is entirely free to try out until January 4, 2021. Even trial accounts will be able to get these freebies, so you can not only give Overwatch a bash and see if it's your type of game, but also get some nifty cosmetics along the way. Naturally, should you decide to buy the game at any point in the future, you'll be able to keep all of your stuff.
Have fun, and just for good measure, I'll leave you with the Winter Wonderland trailer highlighting some of the new items: