What do you even mean??
Gen 1:1-3: In the beginning, God created the heavens and the earth. The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God was hovering over the face of the waters. And God said, “Let there be light,” and there was light.
Gen 1:14-19 (fourth day) And God said, “Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons, and for days and years, and let them be lights in the expanse of the heavens to give light upon the earth.” And it was so. And God made the two great lights—the greater light to rule the day and the lesser light to rule the night—and the stars. And God set them in the expanse of the heavens to give light on the earth, to rule over the day and over the night, and to separate the light from the darkness. And God saw that it was good. And there was evening and there was morning, the fourth day.
ok so yes it says he made a greater light to rule the day, but he had already created light (the sun) he was separating them from eachother (night and day) and also about the day thing, 1. The easy answer is God is God and can do anything. 2. God can’t lie (heb 6:18) so when he says “so was the 4th day” it means that was the 4th day.