Emperor Taishang was the only living person in ancient China who was nominally higher than the emperor. But the power and influence of the Emperor Taishang was "Schrödinger's cat". Some Emperor Taishang had great power and influence, the emperor was at most a crown prince (such as the Qianlong Emperor of the Qing Dynasty), and some Emperor Taishang was in a miserable situation (such as Ming Yingzong). So how much power and influence did the ancient Chinese Emperor Taishang (Taishang Emperor) have?
China's first Emperor Taishang was Qin Shi Huang's father, Qin Zhuang Xiang Wang, who was posthumously enthroned after Qin Shi Huang became emperor. It can be seen from the posthumous appointment of King Xiang of Qin zhuang as Emperor Taishang that Emperor Taishang should not have been a living person in Qin Shi Huang's original design of the emperor system. The first living emperor in China was Liu Bang's father, Liu Taigong, but that was only because Liu Taigong was not dead when Liu Bang became emperor, and he had no power.
The first person in Chinese history to retire from the throne to Emperor Taishang was emperor Hui of Jin (later reinstated) who was overthrown by Sima Lun. The first Emperor Taishang who really had real power was Lü Guang, the Taizu of Houliang. Emperor Hui of Jin was a famous "silly emperor" and Houliang was a divided regime in the northwest, and neither of these had a great influence on the evolution of Emperor Taishang of China. The first influential Emperor Taishang of China was Emperor Xianwen of northern Wei.
In the fifth year of Emperor Xing's reign (471), emperor Xianwen of Northern Wei, who was only seventeen years old, ceded the throne to a five-year-old crown prince (Emperor Xiaowen). Because Emperor Xianwen's abdication was the result of a struggle with Empress Feng, Northern Wei's courtiers strongly opposed Emperor Xianwen's abdication. In the end, Emperor Xianwen reached a compromise plan with Empress Feng and Qunchen: Emperor Xianwen abdicated the throne without handing over power, and Northern Wei's state affairs were still reported to Emperor Xianwen.
Emperor Xianwen set a precedent for the power of Emperor Taishang: the power and influence of Emperor Taishang depended on the outcome of political exchanges with the emperor and his courtiers at the time of abdication. If the New Emperor and his ministers could not get the new emperor and ministers to give him power when he abdicated, then the Emperor Taishang had almost no power and influence, such as Tang Gaozu, Wu Zetian, Tang Xuanzong, Tang Shunzong, Ming Yingzong, etc., which was the common Taishang Emperor.
If the Emperor Taishang abdicated and reached an agreement with the new emperor and ministers to retain certain powers and influence, then there would be an invisible "dual system" in the imperial court, such as Song Gaozong and Song Xiaozong, Song Xiaozong and Song Guangzong, and so on. If the Emperor Taishang could continue to control the supreme power when he abdicated, then there would be almost no power and influence to become a new emperor, such as the Qianlong Emperor of the Qing Dynasty and the Qing Jiaqing Emperor.