The essentials of Thanksgiving have not changed over the years: Special food, family, giving thanks, and delicious desserts.
But the details have changed a lot.
In the 1940s, you might not be dining on turkey, but maybe a roast or chicken. The average feast cost $5.68 — about $48 today.
During the war years, the main dish and side dishes would probably be governed by what was available. And someone would have been missing from the feast — a son, a father, or a brother. In the countryside and small towns, the food would have come at least in part from your own garden. A special pudding might replace a pie, although if there was sugar (unlikely during rationing) and flour, there was pumpkin pie.
In those days in rural and small town America, families played music together before or after dinner, with Dad on the fiddle and brother on the guitar or banjo. Later, the men went hunting with their favorite hunting dogs.
In the 1950s, the feast cost more than $6, or about $44 to $48 today. You would almost certainly have turkey. It's a good bet that a side dish would involve gelatin. Inside your gelatin mold there could be any kind of fruit or vegetables. You would be more likely to see a mincemeat pie than today.
You would see a lot of patterns in the 1950s. The (possibly Formica) tables were decorated with printed cloths of fall colors and fancy dishes. The turkey might be served on a decorative Thanksgiving platter. Everyone dressed up. Dad would surely carve the turkey, and by the 1960s, he was using an electric knife. Everyone wanted to watch the Macy's Thanksgiving Day parade.
Today, the cost of the dinner is higher ($64 in 2022) and the entertainment might revolve around football.