Not really “leftist” is a sloppy word. In ordinary use, we use it to mean socialist, where the state owns the means of production. China has a market economy. It has an authoritarian political structure where unelected goons run the country.
The US is no different. It has a market economy. It has a deep state political structure running politics.
The only difference is in China, we know who the rulers are. In the US, the deep state operatives are well hidden.
Think about it. Who is more fearsome?
Pretty sure you got that wrong. Socialism allows for private production/ownership, but distributes the benefits of that free enterprise to others who don't produce. Communism is what you're thinking of, where the state owns all production and distributes the benefits to all.
Either way, they both are usually totalitarian top-down government run. Even though China cheats in trade and steals, I had big hopes for the Chinese people once HK reverted back to China, along with international investments. Obviously, they are regressing to their old ways.