The New York Times offers a piece by Jonathan Mahler that breaks down all aspects of Trump's legal exposure one second after Biden is inaugurated examines how Biden might “deal with his predecessor’s flagrant and relentless subversion of the rule of law.” Snippet:
The stakes of prosecuting Donald Trump may be high; but so are the costs of not prosecuting him, which would send a dangerous message, one that transcends even the presidency, about the country’s commitment to the rule of law. Trump has presented Biden — and America, really — with a very difficult dilemma. “This whole presidency has been about someone who thought he was above the law,” Anne Milgram, the former attorney general of New Jersey, told me. “If he isn’t held accountable for possible crimes, then he literally was above the law.”
I have read many hot takes on the presupposition that Biden has no appetite to indict. These are all based on a trial balloon he sent up this week. I would urge everyone to be rational. I would love to see Trump die in prison, but I don't fault Biden for not champing at the bit (publicly, or at all) in the same way. He has a duty to rise above, at least to some extent. It is not his job to prosecute Trump (er, the Trumps). Rather, it would be the duty of the Dept. of Justice. Biden has to keep himself distant from any potential federal prosecutions.
Also, remember that New York state undoubtedly has cases against Trump (er, the Trumps) ready to go; Biden has no say in that matter. These would not be slam-dunks, presumably, but — they are probably more likely to materialize.
So, we wait. And part of what we have to wait and see is how egregiously and flagrantly Trump will abuse his pardon power, and what kind of an appetite for retribution that incites in the populace.