The exploits of the Chinese treasure fleets under Zheng He during the reign of the Yongle Emperor are well known, but equally well known is how those same voyages were cancelled and the ships laid up under the Hongxi Emperor. Some of the old narratives (specifically referring to Paul Kennedy’s Rise and Fall of the Great Powers identify this as an example of how the “unified” China had its overseas expansion cut off by a single directive whereas a fractious Europe could always see an explorer travel to a neighbouring polity which may support what its rivals would not.
So this is a bit of a two part question: 1) Why did the Ming dynasty cancel its naval program? 2) What is the current consensus on the idea that unified government in China prevented further Chinese expansion through a single order unlike in Europe?
I can't speak to the Ming fleet, but I can say with pretty reasonable conviction that the notion that united government in China prevented expansion is hogwash. The notion of a stable and pacifistic China, and by extension East Asian order, under the Ming and most of the Qing has most recently been given a new and undeserved lease on life by David Kang, and I summarise critiques of his model in this earlier answer. A major issue with this sort of model is that it looks at the Ming, whose geopolitical approach was indeed comparatively passive, and claims that the Qing continued from it, without bothering to explain the immense expansion of the Qing empire's territorial scope from 1636 to 1757. This long-form post on the Qing conquest of Inner Asia, which mostly condenses work by Peter Perdue on the subject, should be relevant to that.