It's unlikely that ANY president could accomplish more in his first 100 days of office than FDR did , but Joe Biden CAN do quite a few things in that time period to get this country going in the right direction again.
1) His first priority, of course, is to get us back into the WHO. The next step (which is closely related) is to aggressively attack the cornonavirus so that the number of new cases goes down to less than 1000 per day, which is precisely where Spain, the UK, Italy, Germany and France are at today. In case you are wondering, we had 29,000 new cases YESTERDAY.
https://www.worldometers.info/coronavirus/
2) To set the proper tone about accountability, he should award the Presidential Medal of Freedom to both Lt. Col. Alexander Vindman (who just retired from the Army) and Marie Yovanovich (who retired in January).
3) Replace the current cabinet with people who are actually QUALIFIED for their positions (which is not the case now)
4) Have a panel of experts review all 165 executive orders that Trump has issued so far, and reverse ALL of them that harm the environment or immigration.
https://en.wikipedia.org/wiki/List_of_executive_actions_by_Donald_Trump
5) Meet with the members of the G7 as soon as practicable to reaffirm the fact that they ARE our allies
In my opinion, it will take at LEAST 4 years to reverse the damage Trump has done, but here is a partial list that Biden should concentrate on going forward:
Get us back into the Paris Agreement, the TPP, and the Iran treaty.
Reverse, or substantially reform, the 2017 tax bill in order to make it more equitable.
Fully implement the economic plan that he is revealing today:
https://www.washingtonpost.com/opinions/2020/07/09/joe-biden-flips-script-trump/
Reduce, or eliminate, as many tariffs as possible, and put pressure on other countries to do the same
Appoint 4 Democrats to the Postal Service governing board, fire the current Postmaster General, and replace him with someone who has actually worked for the Post Office
Bomb Russia (just kidding) but at least punish Putin for his many misdeeds, including the payment of bounties on our service members in Afghanistan
Fire Bill Barr, and replace him with someone who is qualified for the position
You can probably think of some other priorities, but the list above should be a good starting point.
Before any of that can take place, there will be 3 debates between Trump and Biden. Since the Supreme Court just ruled that Trump's financial records cannon be released to Congress, but CAN be released to the New York prosecutors, this is what Biden needs to say during one of the debates:
"Mr. President, release your tax returns or shut up,"
This is Biden's quote from 2019 , and he released another video this morning about the same topic:
"As I was saying."
Biden, of course, has released 21 years of his tax returns.
Biden quoted the 2019 video this morning, writing, "As I was saying."