No, the magma just boils the water from the underground stream until it is so hot the steam and water are elected out of the hole/vent. If Yellowstone erupts most of middle America would be affected. But it may never happen because the tectonic plates have been moving for thousands of years since the last eruption. We have several old volcanic hills where I live but there are no longer in danger of an eruption due to plate movement.
If Yellowstone erupts most of middle America would be affected
From the charts I’ve seen 2/3s of the country will be the fall out will reach the east coast and to the south and north.