We tend to spend Christmas with our families. We have huge meals together: on Christmas Eve we have dinner together and it is called "il cenone" (literally the big dinner) and then on Christmas day we have lunch. Some people go to Church at midnight and put baby Jesus in the crib in the nativity scene while others just enjoy food and spending time together with their family (that's what I personally do). Meals could go on forever and some of the most traditional desserts are Panettone and Pandoro (people split in 2 different types: those who like the first one and those who like the second one and they could also start arguing about which one is better😂) but Torrone is quite important too. After finishing eating there are lots of different games you can play: tombola which is like Bingo, card games like 7 e mezzo, scopa, briscola, ruba mazzo, sorchetta etc It really depends on where you are from, I'm from Rome and probably people from other cities will call them in different ways.
Basically we spend Christmas eating, playing and slowly falling asleep on the chair cause we ate too much. And of course we put presents under the tree.