If literally 100% of Americans are voting to make Charles III their President, that 100% must include Congress unanimously voting to approve the constitutional

If literally 100% of Americans are voting to make Charles III their President, that 100% must include Congress unanimously voting to approve the constitutional amendment to make him eligible to run for President, and all the state legislatures voting to ratify it. If any of them vote against that amendment, then your premise that 100% of Americans vote for him would be false.