No civil war in the generic sense, I think. As alluded to above, too many people would have to give up an easy life of Amazon and Netflix and pizza delivery, including, if I'm honest with myself, armchair warriors like me. I like to think I would take up arms, but I can't honestly say what would move me from the armchair to the trenches, as it were. The Three Percenters took their name for a reason.
On the other hand, I can certainly see a "resistance" forming. Heck, many people, including me, do that now. I moved to where I am to lay low, do pretty much what I want, and avoid the government. I guess you could call it the Alliance and the Independents - the core planets and the outer planets. Don't wanna get pinched by the feds? Don't call the feds. Of course that only works if the feds stay in the core. I live in the Redoubt, so hopefully have some time before the authoritarians make life overly difficult by taking notice of this part of flyover country.
I could maybe see some states at least attempting to assert state rights and tell the feds to *expletive deleted*ck off. Texas seems to be doing a good bit of that. Again, not really civil war, but resistance of a sort, and maybe more people will be forced to migrate from their home states to states more closely aligned with their beliefs, again, perhaps only to gain some time.
I'll agree with posts up above that if you are looking to see where civil war of a sort starts, or at least ongoing domestic terrorism, look no further than the demographics that might lose welfare, EBT, free phones, etc. The Republicans don't have the balls to do anything more than slightly reduce those handouts, and the dems only want to increase them, but if some calamity "X" were to happen that cut off those payments? That right there will be your violent uprising against the government, and while I said I was unsure what might cause me to take up arms against the government, I can tell you that I would for sure take up arms to fight that crowd, without hesitation. I would see it as no different than defending myself against home invaders.
EDIT: Speaking of "why only 3%?", just take a look at the fallout from 06JAN. While yes, they did arrest some knuckleheads that destroyed property, they also did mass arrests of people, including whole families, who did nothing more than show up on the Capitol grounds. Plus jail with no bail, warrantless searches, people who had "friends and family" turn them into the feds, ad nauseum. I'm betting that whole business has a lot of people re-evaluating how, when, and where they might even speak against the government, let alone do something physical.