It is not clear that the commission established by Mr. Biden will by itself clarify his position. Under the White House order establishing it, the commission is not set to issue specific recommendations at the end of its study — an outcome that is likely to disappoint activists. In his executive order on Friday, the president will create a 36-member commission charged with examining the history of the court, past changes to the process of nominating justices, and the potential consequences to altering the size of the nation’s highest court. The panel will be led by Bob Bauer, who served as White House counsel for Mr. Obama, and Cristina Rodriguez, a Yale Law School professor who served as deputy assistant attorney general in the Office of Legal Counsel under Mr. Obama.