It... depends on what you call peaceful? If Harris wins, we'll almost certainly see a noticeable increase in domestic terrorism from the GOP and its ilk; probably not huge or destabilizing in general, but noticeable. It'll probably be
relatively peaceful, but the country's primary source of political violence is... still going to be itself.
If Trump wins, well, he's been promising to deport tens of millions of people, possibly by deploying military forces at home, and the campaign's made it pretty bloody clear they're not going to be particularly careful in who gets caught up in that. Saying they're going to have one violent day (i.e. literally fucking Kristallnacht). So on and so forth. There's... no way that ends peacefully, even if it doesn't lead to organized or state level resistance. At the population's absolute most supine it's going to lead to a goddamn
shitton of state sponsored murder, and there is basically no chance the population is that supine. Even if that shit gets stalled out, we see an increase of domestic terrorism and political violence by maga fucks feeling empowered, exactly as we saw in the first go around, and a very intentional draw down of federal efforts to stymie that crap.
So, like. You've got one option for relatively peaceful, that still sees a spurt of violence and then likely a gradual calming on that since they'd be dealing with a fed that
isn't going to encourage it. And then another one that is going to be seriously fucking bloody even if they don't manage half of what they're promising
and there's no resistance to it