WASHINGTON, D.C. — At a wide range of departments and agencies, Mr. Trump’s political appointees are going to extraordinary lengths to try to prevent Mr. Biden from rolling back the president’s legacy.

Voters have decided that President-elect Joseph R. Biden Jr. should guide the country through the next four years. But on issues of war, the environment, criminal justice, trade, the economy and more, President Trump and top administration officials are doing what they can to make changing direction more difficult.

Mr. Trump has spent the last two weeks hunkered down in the White House, raging about a “stolen” election and refusing to accept the reality of his loss. But in other ways he is acting as if he knows he will be departing soon, and showing none of the deference that presidents traditionally give their successors in their final days in office.

During the past four years Mr. Trump has not spent much time thinking about policy, but he has shown a penchant for striking back at his adversaries. And with his encouragement, top officials are racing against the […]