HARARE, Zimbabwe — Everywhere he looked, President Emmerson D. Mnangagwa could see his own face. To battle his cold, he sipped a hot drink from a mug adorned with his own head shot. To his left, an aide wore a green shirt covered with the same image. To his right was a large photograph of the president as a young man. His state portrait hung from the opposite wall.

Since seizing power in a 2017 coup from his onetime mentor, Robert G. Mugabe, Mr. Mnangagwa has gradually imposed himself on Zimbabwe — here in Mr. Mugabe’s former offices in downtown Harare, as well as on the country at large.

Though the new president is marketed as a clean break from Mr. Mugabe and 37 years of autocratic rule and economic mismanagement, Mr. Mnangagwa’s opponents now fear he is more dangerous than his predecessor.

The number of government critics charged with “subverting a constitutional government,” a form of treason, during Mr. Mnangagwa’s 21 months at the helm already outstrips the figure during Mr. Mugabe’s 37 years in office, according to a coalition of 22 Zimbabwean rights watchdogs.