Did he say "How he would end the war in Ukraine" on day 1? You have to understand WHY there is a war in Ukraine before you can end it. There is war in Ukraine because the only way to prevent Ukraine's membership into NATO was to enact a war that would immediately trigger the Article V NATO obligations to put US troops on the ground. The fact that Biden has since stated that Ukraine can't join NATO until the war is over means that Putin got exactly what he wanted. Russia doesn't care if the war is a slog. Outside of Crimea, they don't particularly care for the territory. A stalemate is fine for Russia, as long as the war continues.
So to end the war in 1 day, is Vivek (or Kennedy) going to announce that Ukraine will no longer be part of NATO and that they will be declared a neutral country (like Switzerland)? Or are we going to immediately admit them to NATO, and escalate the war to force Putin to withdraw? Those are basically the two options, and I'm not seeing either of them (or any other candidate) honestly talk about this.
Just saying "I'll end the war on day 1" is political lip service.