The Trump administration plans to scrutinize thousands of F.B.I. agents involved in Jan. 6 investigations, setting the stage for a possible purge that goes far beyond the bureau’s leaders to target rank-and-file agents, according to internal documents and people familiar with the matter.

The proposal came on a day that more than a dozen prosecutors at the U.S. attorney’s office in Washington who had worked on cases involving the Jan. 6 riot were told that they were being terminated.

The moves were a powerful indication that Mr. Trump has few qualms deploying the colossal might of federal law enforcement to punish perceived political enemies, even as his cabinet nominees offered sober assurances they would abide by the rule of law. Forcing out both agents and prosecutors who worked on Jan. 6 cases would amount to a wide-scale assault on the Justice Department.

On Friday, interim leaders at the department instructed the F.B.I. to notify more than a half-dozen high-ranking career officials that they faced termination, according to a copy of an internal memo obtained by The New York Times.

The acting deputy attorney general, Emil Bove, also told the acting leadership of the F.B.I. to compile a list of all agents and F.B.I. staff “assigned at any time to investigations and/or prosecutions” relating to the events at the Capitol on Jan. 6, 2021 — the day a mob of Trump supporters stormed through the halls of Congress.