WASHINGTON — President-elect Joseph R. Biden Jr., inheriting a collection of crises unlike any in generations, plans to open his administration with dozens of executive directives on top of expansive legislative proposals in a 10-day blitz meant to signal a turning point for a nation reeling from disease, economic turmoil, racial strife and now the aftermath of the assault on the Capitol.

Mr. Biden’s team has developed a raft of decrees that he can issue on his own authority after the inauguration on Wednesday to begin reversing some of President Trump’s most hotly disputed policies. Advisers hope the flurry of action, without waiting for Congress, will establish a sense of momentum for the new president even as the Senate puts his predecessor on trial.