During the Credits
There is an extra scene after the first set of credits for South Park: The Fractured but Whole.
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.