Twitter will transfer the POTUS handle to Joe Biden on January 20, no matter what. President Trump never used the handle, which is archived by the Library of Congress and has 32.8 million followers, as his main account. He has continued to tweet unhinged rants from his personal account, which has 88.9 million followers, and POTUS retweets the most cogent of these missives.
Joe Biden’s personal Twitter has 19.3 million followers, so the POTUS handle will bump his following. Barack Obama currently has 126.5 million followers. Both Biden and Obama joined Twitter in March 2007, the month it was given a huge publicity push at South by Southwest. Donald Trump sent his first tweet in May 2009 to promote his appearance on David Letterman.