For the major part of that what you say is true. Not just RED/BLUE states. It’s really URBAN VS NONURBAN/SUBURBAN with each state having a leftist highly populated set of cities that can often outnumber the rest of the states. How do you fight that? Not by ‘secession’ - by isolation. Abandon them. Abandon them as a tax base. Abandon them as sellers, providers or merchants or suppliers or middlemen. Abandon them as Americans and move on without them.
They will end themselves if left alone and not helped.
Sorry but abandoning cities is abandoning the major infrastructure, the architecture, the museums and libraries of civilization. Are you gonna say to your ancestors “We decided to not fight for what you built for us, I will be content instead sitting in my trailer house watching some gay sport like football instead”