Trump Claims He Can Use Executive Order to End Birthright Citizenship

[Angrboda]

But if this makes it to the Supreme Court, they could just rubber stamp it.

The Supreme Court cannot amend the Constitution, either.

No, but the Supreme Court can redefine how the amendment is interpreted. I don't foresee the current Supreme Court doing that, even given it's conservative bias, but then, stranger things have happened. It would undermine confidence in the courts, politics, Republicans, and the rule of law, but I can't see such a decision leading to anything as serious as civil war, given that the outcome of such a result would not meaningfully impact most Americans.