Sure. The prime minister was a general term or a common name for the highest administrative officer under the ancient Chinese monarch. It was not a specific official name. In the Ming Dynasty, the chief of the cabinet was called the prime minister on some occasions. Although they generally did not use this title in their official name, their roles and responsibilities were similar to those of the prime minister. Therefore, it could be said that the chief assistant could be called the prime minister.
I'm not sure specifically as I haven't fully watched it. But generally, in such movies, the ending could be about the chief minister achieving some great political victory or making a significant impact on the lives of the people she represents.
In the Ming Dynasty, the chief assistant of the cabinet was not the same as the prime minister. In the Ming Dynasty, the system of cabinet chief assistant was completely different from that of prime minister in terms of system setting, organization operation, responsibility orientation and power nature. In the Ming Dynasty, the chief of the cabinet was the emperor's consultant body, helping the emperor to review memorials and put forward opinions and suggestions. The prime minister was the head of the civil officials and had the power to supervise the country on behalf of the emperor. Although some people called the chief assistant of the cabinet prime minister, this title was just a habitual statement and had no practical significance. In the Ming Dynasty, the chief of the cabinet did not have the power and status of the prime minister. Therefore, the chief assistant of the cabinet could not be equated to the prime minister.
The difference between a cabinet chief and a prime minister lay in the actual size of their power and the difference in their duties. The prime minister was responsible to the monarch and was in charge of government affairs. He had actual power and was in charge of government affairs. The chief assistant of the cabinet was the number one assistant minister in the cabinet. He provided suggestions to the emperor on government affairs. He did not have actual power, but only held the power of voting. The cabinet chief assistant was equivalent to a secretary, mainly providing suggestions on government affairs, while the prime minister was the highest administrative chief who was actually responsible for handling government affairs.