Taiwan did not, and neither did Vietnam. Both countries had virtually zero cases until new variants arrived.
In the case of China, reports from Wuhan said that 5 million people had already left the area for the New Year holidays, shortly before the lockdowns. They travelled on crowded trains and buses all over the nation, yet there were only minor outbreaks.
The assumption in the US has been that China has been lying about its COVID cases and deaths. My observation is that the reported cases and deaths in Vietnam and Taiwan were consistent with the low numbers reported from China. In that context, it is likely that China’s numbers are not grossly out of whack.
A reasonable explanation for the lack of massive epidemics in China, Taiwan, and Vietnam is that the populations already had herd immunity to the early versions of the virus. That immunity became less effective only after new variants appeared.
