Why is the Earth's axis at a certain angle? What would happen if it was 1 or 2 degrees off?
no one knows; and, a lot
No one has an explanation for the earth being 23.5 degrees of the solar plane. Good thing it is because that is the reason we have our seasons.
A degree or two plus would most likely be devastating. That would mean at the height of the summer in either the northern or southern hemisphere, not only would the length of the summer for the poles increase, but it would likely mean the end of the polar caps. The polar caps in both hemisphere a crucial to the ocean currents which run north/south/north.
A degree or two less would not be devastating but would radically change the growing seasons for people in the more northern climes. There would be a general shift northward/southward, depending upon the hemisphere, of heat. But that could mean an expansion of existing deserts with the possibility of new deserts being created.