Certainly, He could.
But then, when one refers back to the Bible, we see that the evening and the morning were the first day, followed by the evening and the morning of the second day, and so on. Light as “day” and darkness as “night” were defined.
So, that argument is thrown back upon itself.
But what do you make of the fact that the sun was not created until the fourth day? Plants and trees and vegetation, all needing sunlight for photosynthesis, were created on the third day.
It seems to me that if the days were ages, the green stuff would have died long before the sun came along during the Day 4 age.
What say ye?