There are many monarchs who are born with visions, and the descriptions are very exaggerated. However, some visions are artificially compiled to give the king a magical color and make people feel that they are born with visions. This king was destined by God to be the True Dragon Emperor, so that his subjects would be more convinced of the king and be conducive to his rule.
Everyone knows that Song Taizu Zhao Kuangyin was the founding king of the Song Dynasty. It is said that he had a unique fragrance when he was born, and Zhao Kuangyin still had a red light lingering on his body a few days after he was born. Moreover, Zhao Kuangyin's skin is yellow, which is very strange anyway.
When Emperor Wen of Wei Cao Pi was born, it is said that seven-colored clouds appeared in the sky and never dissipated. Therefore, some people said that Cao Pi would be very successful when he grew up.
When Ming Taizu Zhu Yuanzhang was born, it is said that Zhu Yuanzhang’s mother had a dream when she was giving birth to Zhu Yuanzhang, and then she dreamed that a god gave Zhu Yuanzhang’s mother a magical elixir. After Zhu Yuanzhang's mother gave birth to Zhu Yuanzhang, red light appeared all over the house, which was considered a natural phenomenon.
When Emperor Wu of the Han Dynasty Liu Che was born, it was said that Liu Che's father dreamed of a magical pig riding on a red auspicious cloud and flying to the place where Liu Che's mother lived. Then Liu Che was born soon after. In the past, everyone knew Liu Che's name as Liu She, which means pig, which means Liu Che is the reincarnation of an auspicious pig.
Anyway, emperors have more or less magical legends. Even if there are no natural phenomena, there will be historians who will compile some magical experiences for them to make them more important in the eyes of the common people.