Assuming Biden is elected, here are a few things he could immediately do that would make me feel better. In no special order.

1) Close Guantanemo

2) Commute the sentences of prisoners, mostly black women, sentenced under harsh mandatory sentencing guidelines for minor drug offenses.

3) Nail down universal health care.

4) Immediately fully reinstate effective as of their date of being fired or reduced every federal employee fired by or forced to resign or reassigned by Trump not for legitimate cause. Think Sally Yates, for example, and Marie Yovanovich and Alexander Vindman and Andrew McCabe, et al.

5) Announce a full, complete, comprehensive criminal investigation of all things and persons Trump. Not as a witch hunt, but as a combined effort to identify crimes and criminals and punish them, fully document the history, exonerate any who can be, and within the history to identify the lies and the liars, and the cost of the lies. That is, to heal wounds, they have to be cleaned out.

5, i) For example, Trump presumably files and pays taxes. Either he has broken laws or he hasn't. There is much anecdotal evidence that he's almost never met a law he didn't break. Did he break any tax laws, and if he did, he needs proportional punishment. And if he did not, if a complete investigation of his taxes across years reveals he broke no laws, well then, good for him! But I doubt that's the case.

6) Reverse every rule, law, directive issued by the Trump's administration. I cannot think of one that is not rotten, obscene, disgusting, and corrupt.

7) Commit to reuniting every child separated from their families by Trump, and provide - or at least offer - citizenship to each such child and his or her family.

8) Invite the Mexican government to officially participate in a wall-destruction program. A joint artillery exercise where possible would be nice! But repudiation by total destruction.

edit, forgot one.
9) Review all appointments under Trump to the federal judiciary, disqualifying - and prosecuting - for cause any found to have lied about their qualifications, or for any other appropriate reason.

And anything anyone thinks should be added. Of course Biden's administration will have a lot to do that has little or nothing to do with Trump. But this listing should be limited to just those things he should do to repair and rehabilitate after the disease that is Trump.