The dry ice will bring the box temp down and keep the food cold but I think there’s a balance there because I doubt the fridge is running much when the dry ice is keeping things cool. Then the dry ice sublimates and the fridge has to take over. I sensed a “bounce” when that happens. Stopped in a
Smallish town in Nebraska a couple years ago and got a few groceries. Asked if they had dry ice. They did and the lady bagged up a brick for us. At the checkout they did not charge us. When we pointed that out they said “Oh there’s no charge, we do that for the ranchers who have a long drive home and don't bring a cooler.” By night we were in the Colorado mountains and it cooled off and everything leveled out.
Strike while the iron is hot. Live every day as if it were your last and one day you will be right.