The Day After is the best of the nuclear holocaust trio, the other two are Threads and Testament.
Threads is a British take on nuclear war. It has one element that is interesting in the last 20 minutes or so, in which it jumps about a hundred years into the future and shows a devolved humanity living a bleak, starved existence.
Testament as I recall, doesn’t have any immediate devastation, as it shows a small town gradually get radiation/fallout sickness and die off. It’s all around a rather cheap production.
If you want to be terrified, I recommend The Atomic Bomb Movie.
I thought Threads jumped ahead 10 years, not a hundred.
And yes, the thing that stuck with me, was how quickly language became dumbed-down, because the kids didn’t really go to school. The scene where they are watching on old video, where they talk about skeletons.
The other thing in Threads were those creepy “Protect And Survive” videos, they have the full versions of them on YT.