During the Credits
There is an extra scene after the first set of credits for South Park: The Fractured but Whole.
In first extra scene, the New Kid returns home where both of his parent are revealed to still alive. They explain that they’re happier than ever after revealing the secret they were keeping so long of the New Kid’s origins.
The New Kid’s parents then go upstairs to have sex. Outside the parents door, the New Kid stands there in silence as Professor Chaos shows up and reveals the one truth in this life, “No matter how hard you try to change the past… your dad will always fuck your mom.”
After the Credits
There is extra gameplay after South Park: The Fractured but Whole.
[spoiler]After the credits are complete, the New Kid is returned to town where the player can continue exploring and completing sidequests.