Not a civil war, no.
But the USA will divide into two, or three distinct geographical sections, based on state borders.
The more populous east and west coast blue states will basically ignore, defer, delay or otherwise refuse whatever federal proclamations may come from the White House or even from Congress, and continue to run themselves as the hugely prosperous centers they are now. California has already been "Trump-proofing" itself. Nothing much will change for them, except perhaps to not collect taxes for the federal coffers but keeping more for themselves. That's a lever yet to be exploited, btw.
The remaining red states, geographically central - the flyover - will go full Trumpy-MAGA, and welcome and implement each and every fascist federal law with cheers. They will go basically backwards off a cliff socially - the Christian Taliban realised. Some states may still be generating a bit of tax revenue, but the previous financial support from the blue states will dry up, and they will all get noticeably poorer. Standards of living will drop even further. But at least all the brown people...sorry, illegals...will all be deported, even though that will cripple many primary industries. So there's that. And they will console themselves that, while they may be crushingly dirt poor and getting worse, but at least they are not socialist, commie lefties.
In effect, the current state of affairs between states will become far more exaggerated, and eventually the situation will become like separate countries within a country. No civil war need