I don't think it is sensible to talk about having a Ukrainian level war without also having the Ukrainian scenario or context i.e. being invaded by a next door neighbor with a powerful military.
I feel like there are a whole bunch of important tactics lessons to be learned, like dealing with small grenade dropping drones, but the way that the United States conducts war is pretty different.
If the United States somehow found itself needing to repel and invasion, it is pretty obvious that enlistment rates would suddenly be very different.
Context matters.