How would I know? I am a Bolognese.
There is not a single Italian Christmas menu, as regional traditions are profoundly different.
In Bologna, the first course of the Christmas lunch is “tortellini in brodo”. This is a type of pasta filled with pork and cooked in a meat broth. Bolognese would either make their own tortellini or buy them from artisan pasta shops, as the factory-made variety does not compare favourably.
Bologna is the capital of the Emilia-Romagna region. Ferrara is only thirty miles away from Bologna, but it has its own distinctive different recipes. This in part reflects history: Bologna was an independent free municipality, subsequently ruled by the Pope. Ferrara was a separate state ruled by the Duke of Este.
Sixty miles to the East of Bologna is Parma, which was the capital of an independent Duchy. Parma is known for both Parma ham and Parmesan cheese. Both Parma ham (known in Bologna as “prosciutto crudo”) and Parmesan are critical ingredients of tortellini and of other Bolognese recipes.
Interestingly, Parmesan made just to the east of the river Reno (the river of Bologna) is known as Parmigiano-Reggiano, but an almost identical cheese made to the west of this river is known as Grana Padano.

Photo from wikimedia commons

My paternal family had a farming background and most Bolognese farmers reared chicken and pigs. Cockerels were castrated and fattened for Christmas. Thus, a roasted capon was always served as a second course on Christmas day.
Bologna lies in the Po valley, which used to be covered by marshes and swamps and is still criss-crossed by rivers and drainage canals: this influences what Bolognese eat.
On Christmas Eve the Italian tradition is to eat seafood, rather than meat. My mother served “capitone” (eel stew) to my father. Mum, though, would never eat capitone or frogs (another local delicacy) as she came from Ancona, a maritime city, and she thought that only sea fish was worth eating.
Cod features in many Italian recipes and in some Christmas eve meals. It was a Venetian merchant who started importing cod to Italy some 500 years ago. In the absence of refrigeration, cod was had to be imported as dried fish (known as stoccafisso) or after having been salted (known in Italy as baccalá). Both are cooked with Mediterranean flavours.
Thirty miles East of Bologna is the city of Modena. In 1325 Modena (supported by the Holy Roman Emperor) fought against Bologna (supported by the Pope) in the Battle of Zappolino. The victorious Modenese took some spoils including a wooden bucket. A facsimile of this bucket is still prominently displayed inside the Ghirlandina tower in Modena and has become a symbol of the rivalry between two neighbouring cities.
Modena’s contributions to the Christmas menus includes two pork meat products. Zampone is pig’s trotter stuffed with spicy ground pork. Cotechino is somewhat similar but leaner. Both are boiled in water and served with lentils and mash potatoes.
Any Christmas meal should conclude with a cake. Panettone is ubiquitous in Italy: it originates from Milan and is usually bought, as it is actually quite difficult to make.
Northern Italy started to cultivate rice in the 15th century and Torta di Riso (rice cake) is a very traditional and easy-to-make Bolognese cake.
However, there are two other cakes in Bologna that are more specifically associated with Christmas: Certosino and Panone. Both belong to a European tradition of making winter cakes that last long after baking and utilize honey, candied fruits, and nuts.

Certosino dates back to the Middle Ages and was originally produced by the monks in the Certosa monastery of Bologna: they got some reputation as they started sending their cakes to Cardinal Lambertini in Rome, who subsequently became Pope Benedict XIV.
There isn’t much of a national cuisine in Italy. Every region or city has its own traditions, often steeped in history. Italy has seen the rise of a Slow Food movement, as an antithesis to fast food, with the aim of defending regional traditions as well as good food.