That raises an interesting legal question.
She will not be 35 years old until December 13.
She would be 34 on Election Day.
She will be 35 on Inauguration Day.
Valid election? Valid President?
I think the idea is absurd…but, as long as you are of the age on Inauguration Day, it’s valid. Biden was 29 when he was elected Senator, he was 30 on November 24(?) after the election.
Perfectly legal either way—to a democrat.