If it's against the law, and the POTUS does it, then he/she should be in fear for their personal liberty. A case like you describe might end up in SCOTUS to see of there was Congressional overreach. But, no one is above the law. Not a Representative, not a Senator, and not POTUS. Whatever the law may be.

Wasn't it Bush who had to get congressional approval to take action in Afghanistan? And he did it, and I think Obama continued to use it over a decade later. But they did it legally. If Congress were to rescind that authority, well then it is rescinded. No one should be above the law.

Even on immigration recently. Both Trump and Biden tried to violate the law, and both got slapped-down. Because it's the law. If a prosecutor could make a case strong enough to go to trial, so be it. I want people of power second-guessing if they are treading to close to "the line".