@mikeflstfi: I cannot imagine what a natural 327 would do. It might do so much damage that it causes damage in the past and prevents whatever's being hit from ever existing and thereby changing the entire timeline.
Player: Natural 20!
DM: Checks DM screen.
Player: What's my damage bonus?
DM: Everyone reroll new player characters?
Players: WTF?
DM: The dragon's not just dead. It never existed, and so there was never any hoarded treasure in the mountain. In fact, you did so much damage...
...that the dragon's bloodline going back 51,561 years never existed. Instead of the original Council of Five Dragons, there was a Council of Four Dragons, and so they never broke the deadlock on the vote to try to destroy the Dwarves and Elves. So the Dragons, Dwarves, and Elves became allies and then friends as species. So when the Orcs and Ogres came along, they vanquished them in a fortnight, everywhere. So there's been peace and harmony for millennia, and so you all now...
...need to roll up... (checks notes)... from the new classes of Farmer, Merchant, Teacher, Builder, Ranger, and Generic Person.
Player: What about Fighter?
DM: There's not been war or even fighting, beyond fitness martial arts, for over 50,000 years.
Player: What about Priest?
DM: No misery, strife, or war in over 50,000 years. So no need for salvation or crusades or whatever.
Players: ...
Player: Can I reroll?
@thedisasterautist
I would think the "natural" 20 would do significantly more than double damage then.