"What about" Pay Caesar's things to Caesar and God's things to God?"
What about it? This whole interaction is obvious.
Matt 22:15 Then the Pharisees went and conspired together in order to trap him in his speech
16: So they sent their disciples to him, together with party followers of Herod
17 :Tell us, then, what do you think? Is it lawful* to pay head tax to Caesar or not?”
18 But Jesus, knowing their wickedness, said: “Why do you put me to the test, hypocrites?
Jesus knew that if he said yes, Pay them. They would accuse him of siding with the Romans.
If he said No, don't pay them. Then they would bring accusations to the Romans that he is teaching not to pay the tax.
So he declined to answer the question, but he referred to the coin and what it showed so they answered the question themselves. Jesus was good at sidestepping their questions.