You couldn’t write a better thriller:
A Machiavellian power wanted to start a Civil War. They first released an engineered virus that caused tensions to skyrocket. Then agitators began rioting and civil unrest that put everyone on edge and made them suspicious of the other side.
Then they screwed with the election in an obvious way, ending with Biden getting elected, but with the right pissed off that they were cheated.
Then they lit the fire of civil war by getting rid of the President just a few weeks after his inauguration by having him assassinated in a public way, and the assassin was an apparent right wing gun nut right out of central casting who used an AR-15 that had been modified to fire full auto (or used a bump stock).