As reported by engadget,
Several accounts from the Biden camp will then take over those usernames. Twitter will convert @Transition46 to @WhiteHouse, @PresElectBiden to @POTUS and so on. One username that won’t make the transition is @SecondLady. Instead, Harris’ husband, Douglas Emhoff, will use an account called @SecondGentleman. Twitter will archive @SecondLady as @SecondLady45, and the current handle won’t be in use for the time being.
Unlike the 2017 transition, the new versions of those institutional handles won’t automatically hang on to their existing followers. If you follow any of those accounts, or the Biden camp ones that will be converted, you’ll see alerts and prompts about the switch, along with the option to follow the new versions.
Live streams of the inauguration ceremony will be available through Twitter’s US Elections Hub, as well as the @JCCIC and @BidenInaugural accounts. The hub will include lists, moments and recommendations of accounts to follow.