PA thinks they can change voting rules for Federal Office?Yes.
No. The issue is that PA Act 77 authorizing mail in voting en mass, required a constitutional amendment. The constitutional amendment never occurred in spite of the fact that the process was initiated and abandoned. The PA Supreme Court let that stand, however the office in view here is the President of the United States, making it a federal issue. Therefore, the US Supreme Court may have something to say about the fact that the Pennsylvania election violated the Pennsylvania Constitution. All of the mail in ballots were unconstitutional. So applying the big laws to the little ones, the Pennsylvania Constitution [the supreme law of Pennsylvania] trumps PA Act 77.