Chinese foreign policy has been fairly cautious and covert compared to other world powers. I think this has generally been a good strategy as it has avoided major conflicts with the US and Europe in recent times.
I can’t think of any coup they’ve directly supported but they certainly have supported military movements and governments in other countries, including Vietnam, North Korea, Myanmar, and Venezuela. So they’ve been a bit less prone to overthrowing governments but they aren’t afraid to use similar tactics to keep friendly regimes in power, and help those factions expand power. So is it a coup to help the North Vietnamese conquer the South? I guess it depends on the definition of coup which can be a fraught word.
Personally I’m not sure I see any of these as coups. The closest might be Myanmar but while China has protected and supported the junta there, it’s not totally clear they actually supported the coup itself. I interpret their actions as seeking stability and wanting to minimize Western influence.