Genesis 1:1 In the beginning God created the heaven and the earth.
According to Solomon (speaking by the inspiration of God); God exists outside of his creation.
1 Kings 8:27 But will God indeed dwell on the earth? behold, the heaven and heaven of heavens cannot contain thee; how much less this house that I have built?
2 Chronicles 2:6 But who is able to build him an house, seeing the heaven and heaven of heavens cannot contain him? who am I then, that I should build him an house, save only to burn sacrifice before him?
2 Chronicles 6:18 But will God in very deed dwell with men on the earth? behold, heaven and the heaven of heavens cannot contain thee; how much less this house which I have built!
To be clear - God existed before he made the heavens. That which is eternal is God himself alone; not God and something else.
Nehemiah 9:6 Thou, even thou, art LORD alone; thou hast made heaven, the heaven of heavens, with all their host, the earth, and all things that are therein, the seas, and all that is therein, and thou preservest them all; and the host of heaven worshippeth thee.
We conclude that the heaven created in Genesis 1:1 is the heaven of heavens. The heaven in v.8 is Earth’s atmosphere.
Genesis 1:8 And God called the firmament Heaven. And the evening and the morning were the second day.
I hope you have found this helpful.