Trump already knows that there aren't any rules. He lies repeatedly. Sometimes he lies and then denies the lie in the same sentence. He creates "enemies" and fall guys that he can blame for either the opposition to him or anything that goes wrong while he is President.
He constantly calls the news "fake" unless he sees a story he likes. Then the "fake" news outlet doing the reporting is suddenly doing a great job. Trump knows that the press is not fake, in fact, he has courted it his entire adult life. He says it because it puts seeds of doubt in the minds of his base any time a negative story about him appears.
While he continues to brag about the economy, he is also preparing in case it goes into a slump during his Presidency. That is why he is constantly attacking the Federal Reserve Board. If the economy slows or stalls while he is in office, it won't be his fault. After all, nothing ever is. Instead, he will put the blame on the Fed.
Lately he has begun to claim that attacking or opposing him is the same as attacking or opposing the United States. It isn't of course, but he's getting away with it for two reasons. One is that around 35% of the people will believe anything he says without question. If he told them to drink poison, they would do it. The other is that when it comes to the subject of government, most of "we the people" have no idea how it works. Ironically, most of the people who attend Trump rallies and cheer wildly when he rails about immigrants, couldn't pass the civics test those people have to take to become citizens.
The only possible way that the madness may stop before 2025 is for Republicans in Congress to stop whispering about how unfit Trump is, and start saying it out loud. And that is not going to happen. As I have said many times, for every member of Congress, job number one is to get reelected. Republicans are afraid that if they even mildly object to something Trump says or does, it will cost them their seat. As a result, instead of standing up for their country, they continue to enable the President's behavior.
To be fair, both parties put power and office above country. If Trump had won as a Democrat, that party would be meekly following him. The difference would be that the Republicans are much better at being the opposing party. They would have no trouble building a case for impeachment against him. Heck, they were able to impeach Bill Clinton for lying about an affair. If they could do that, with Trump they could have lynch mobs standing outside of the Capital, just waiting for him to come out.
But that's not the way things are. Instead, Trump will continue to do as he pleases and getting away with it. Republicans will continue to defend him in public while saying in private that he is unfit. Democrats will continue to lob spitballs at him and getting nowhere. It's like depending on the Keystone Kops to bring down the Mafia.
Meanwhile, the people lose.