Missing the point by desperately seeking
any superficial thing in common, are ya.
Odd it is that both liberals & conservatives
think of Jeff Davis as a US President in
pursuit of the claim that they aren't above
the law.
Nobody said, nor does anybody think that he was a US President. This is a matter of insurrection, treason, and the Federal government's response to it. That's what both situations have in common. It's not so much about which offices Trump or Davis held, but about the Federal government's response.
Jeff Davis was certainly not above the law, but he was ultimately released and given amnesty, just like thousands of others who joined up with the Confederacy. That was for reasons of political expediency, although there were those who wanted to punish the Confederates more severely, but they didn't really get their wish. Other political forces took precedence. Grant also wanted reconciliation.
Likewise, neither Trump nor anyone else is above the law, not in any legal sense. There's no unwritten tradition or any great public sentiment against the idea of a President being incarcerated. It's just that, historically, it's been kind of rare that the question has had to be considered.
The Federal government certainly has the power to imprison or otherwise punish Trump if and when he is found guilty of his crimes. It's merely a question of who will wield that power and how they will use it. In essence, they
are the law, so in essence, whatever they choose to do in exercising their legal authority is within the framework of the law. But they're the ones with the power, not Trump.
To me, "above the law" means having the power to override anyone who can try to enforce the law against you. Trump doesn't have that power, not when he has to depend upon the kindness of strangers (or the wrath of his cult following).