I don't think you can make your son speak English. However, I'd say that he will pick it up in no time once he's in school and around children who speak English.
It takes time. We moved to Mexico in November 2021, and our Spanish is still not great. I thought my youngest would pick it up in no time but it's actually my teen daughter who's best at Spanish. All kids are different. He'll get there.
Just don't make the same mistake I did when we lived in Ireland as a Dutch family. I started speaking English more and more and before I knew it, my kids refused to speak Dutch. I now regret not speaking Dutch with them because it would have been good if they would speak it.
Anyway, I hope you had a great day>