Say I wanted to open up a bank account but I owe money for child support is it possible for them to dip into my account without consent

If they get a Judgment or Order against you, yes. Bank accounts are not protected assets when it comes to child support.

You have money to open a bank account but no money for child support?

Yes, they can get a judgment against you and freeze the account. They can also suspend your license, place a lien against your personal property, put you in jail, etc.

I think the bigger issue is that you're not paying the ordered support; what's your reason for that?

Yes. They can put a lien on your bank account as a remedy for enforcement.