Pharaoh thinks he is in control. He is seen as god. His heart (his divine will) controls life in Egypt. But God will make it clear to the Pharaoh that God is in control. Pharaoh will refuse to listen to God and obey him. He does not obey anyone (see Exodus 5:2). But God will force him to obey. Not at once, but God will make his heart hard. Pharaoh will be more and more determent not to listen to Moses and his God. In this way God will show his power (Exodus 9:16). The credits for Israel’s liberations are for God and no one else: he is working out his plan. That has to be clear to Israel (Exodus 10:2) and Pharaoh and his people (Exodus 14:4).
At the same time Pharaoh is not a victim of God’s decision to harden his heart. He can make his own choice and has a responsibility. Pharaoh hardens his own heart (Exodus 8:15). Only after the fifth plague (and further on) we read God hardens his heart (Exodus 14:4). Sadly, the king of Egypt would not repent of his sins and the Lord gives him over in his sins (see further Romans 1:24; Romans 9:14–18). God hardened the hardening heart, until he decided in his wisdom that it was enough, and his mighty hand made Pharaoh let God’s people go (Exodus 3:19–22). God includes Pharaoh and his decisions in his plan. He is in control and brings freedom to Israel by judging the Pharaoh. He gains glory for his name (Exodus 14:4). See the song of Moses and Miriam in Exodus 15:18 which reads: The Lord reigns for ever and ever.
21 And the LORD said to Moses, “When you go back to Egypt, see that you do before Pharaoh all the miracles that I have put in your power. But I will harden his heart, so that he will not let the people go.