Self-enforcing (edit: actually self-executing is the proper legal term) here means that the constitutional amendment doesn’t require a separate act of Congress. The opinion addresses this and says if the 14th Amendment wasn’t self enforcing (edit: executing), some absurd results would ensue. One would be slavery would still be legal.
That’s kind of a cool idea, but depending on where you are this is illegal and/or unethical as lawyers have a fiduciary duty to represent their client’s best interest.
https://www.stimmel-law.com/en/articles/fiduciary-duty