From Food magazine:
The tradition (of dining at a Chinese restaurant) probably originated in Manhattan, where Jewish and Chinese immigrants clustered in neighborhoods near each other. Rabbi Joshua Plaut also theorizes in his book, A Kosher Christmas: ‘Tis The Season To Be Jewish, that because neither culture celebrates the holiday, they’re “outsiders” on Christmas” so there’s an inherent affinity there. Plus, Chinese restaurants tend to stay open every day of the year, holidays be damned. Whatever initially drew diners to Chinese restaurants on Christmas, they’ve become a beloved destination for holiday feasts on both coasts, and everywhere in between.
She goes further: “Christmas Eve and Christmas Day, we make the joke that it’s our Super Bowl. It’s extremely busy, and people rely on us to be there for them,” Rose says. At Genghis Cohen, both dates are hopping for dine-in and takeout. Christmas Day probably sees a bump in dine-in reservations. “People make reservations almost a year in advance. When they walk out of the restaurant on Christmas Day, they make a reservation for the next year.”

Bottom line, I hope the restaurants make huge profits for staying open. I can honestly say that I have enjoyed Chinese food on Christmas only a few times in the past. I had a Chinese girlfriend, whose Mom and family were great chefs. I never missed the turkey or ham.
Growing up, our family enjoyed tamales from my Uncle’s foreman on the ranch, and my Dad’s chief mechanic. They made different styles of tamales, but we enjoyed both. In fact, we preferred the tamales to our turkey dinner at both Thanksgiving and Christmas!

Many Italian families I know always prepare seafood on Christmas. My cousins always make a prime rib.
Of course, in Japanese families, New Year’s Day is the biggest celebration of the year, food wise. The traditional Shogatsu is celebrated throughout the day on January 1. It was always a highlight when my family had these celebrations. Sadly, we no longer have my Mom, grandmothers, or aunts around to make the traditional food.
Whatever you do, stay safe, enjoy the food and family. It is a special day no matter how you celebrate!