I can't even begin to fathom what a war with Iran looks like, other than a whole bunch of innocents dead.
It would be bloody on both sides' militaries for sure. Unlike Iraq, Iran has the ability to hit US bases in the Persian Gulf (Kuwait and Qatar) to include the actual CENTCOM Headquarters.
Iran has so much airspace and such rugged terrain that the air campaign would be more like it was over Kosovo in the 90s than Iraq in the the Gulf War with trees and mountains etc... that mask AAA/SAM.
It would probably get Saudi Arabia involved directly and thereby a much larger and very 'hot' war for the entire region. How it would play out for our Troops in Afghanistan would be an interesting question and how Iraq's pro-Iran government would act would be questionable to say the least. I'd also wonder how Turkey would act, for 2003 they didn't allow the US of their territory to invade Iraq, if they did the same for Iran then the US would be effectively limited to Naval Aviation until it could establish more bases not within striking distance of the Iranian Air Force.

All that aside, I think we were closer to going to war with Iran under George W. than under Trump. Despite his talk about how strong the military is now it's really no better or worse than two years ago, though no longer worrying about budget sequestration.

This is probably just his trying to appear Strong for the whole MAGA thing not to mention distract from the continual fallout from Helsinki showing him as a Russian stooge together with Mueller Probe, Manafort trial, and the Russia/NRA woman.