Since the storming of the Capitol on Jan. 6, 2021, a clearer picture has emerged of the steps that President Donald J. Trump and his allies took to try to keep him in power and overturn the 2020 election. One of the biggest questions, however, has been how far was Mr. Trump willing to go in using the apparatus of the federal government to stay in power? The Times has uncovered that in the weeks after Joseph R. Biden Jr.’s victory, Mr. Trump considered using the levers of the federal government to seize voting machines in swing states. What exactly did Mr. Trump do, and will this revelation tip the scales of the congressional effort to hold him legally accountable?