If you could introduce a Constitutional Amendment What would it be

[Okay, maybe Mike Johnson is a competent parliamentarian.]

Another good one would be a constitutional amendment to ban political parties.

That's typically something that only weird dictatorships and absolute monarchies do. Parties are, at the very least, important to democracy because they give voters some broad sense of what sorts of nationwide policies they're voting for, rather than just voting in some clientelistic clique of local notables. They have many other important functions as well.

[Okay, maybe Mike Johnson is a competent parliamentarian.]

Dramatically curtail the powers of the Senate to bring it more into line with other unrepresentative upper houses around the world, depoliticize the process of appointing federal judges, abolish the Electoral College and federalize presidential (but only presidential) elections, and establish an affirmative constitutional right to vote rather than merely delineating specific bases on which the franchise can't be restricted.