My son is now 23. I found out not only did his dad lie about his income, he is
Very wealthy. Do I have any legal grounds?

What does your child support order say?
If it says he has to pay through college and your son is going to college you may be able to go back to court to have the order amended. Otherwise you can only get him for back child support. It is too late to get any back years increased.

My son is now 23. I found out not only did his dad lie about his income, he is
very wealthy. Do I have any legal grounds?

Legal grounds for what?

Did you have a support order in the past? If so, that can be enforced. If not... well... sorry - you're out of luck.

My son is now 23. I found out not only did his dad lie about his income, he is
very wealthy. Do I have any legal grounds?

No legal grounds but a lot of sour grapes.