Question for the historians: Has there ever been a time when an autocracy has been replaced by a democratic government without political violence or all-out revolution?

I see the US quickly turning into a Putin-style system after Trump solidifies the trifecta of the senate, the judiciary, and the administrative branch. The fourth and fifth “branches”, the media and business, are already bending the knee to his threats.

How can this oligarchy ever be reversed? Seems like a one-way street, historically: China, Russia, NK, Iran, Cuba, etc.

When authoritarians have been ousted, it has been bloody: the revolutions in America and France, Civil War, WW2.