The War Powers Act is questionable. The US never declared war in Vietnam. The president simply sent troops to Vietnam knowing that they would end up fighting. But the president said he had that authority as commander-in-chief. The War Powers Act was supposed to address that.

If the president actually has the authority to send troops into combat without a declaration of war, then Congress can’t take it away from him, just like Congress can’t make it illegal to veto bills.

The War Powers Act doesn’t really set any punishment for the president if he ignores it. It effectively says that if the president does certain things (consult with Congress, follow certain timelines, issue reports) then Congress won’t complain. Presidents have generally followed those procedures without admitting that’s what they’re doing (they issue reports “consistent with” the Act, but never admit the report was required by the Act). But if a president completely ignores those requirements, Congress has to figure out what to do about it; which is exactly what would happen if the Act didn’t exist.