President Biden's U.S. Citizenship Act of 2021 has zero chance of becoming law in present form. While it may become law if Democrats are willing to do some major horse trading with Republicans, currently the chances of that seem scant.
Biden's plan would permit the undocumented to apply for a temporary legal status and then parlay that status into lawful permanent residency after five years. Certain classes of immigrants could be eligible for permanent residency without any wait such as DACA, TPS grantees, and agricultural workers.
However, Biden can make significant changes to immigration policy without his proposed legislation becoming law. First, he could grant TPS (Temporary Protected Status) to noncitizens who cannot return to their home countries due to a crisis there, i.e., COVID-19. Second, Biden could permit a broader swathe of noncitizens to apply for parole-in-place so that they do not need to return to their home countries to become permanent residents. Third, Biden could allow would-be immigrants waiting for their visa numbers to become current to wait inside the United States.