By limiting imports and offering alternatives in home. Also, the myths about reliability ads a lot.

The same way Chinese tech companies “compete” with Western ones: By not permitting them to do business in China.

Tarrifs mostly

On long-term support and parts availability perhaps - I seriously doubt most of Chinese models bought now will have parts readily available in 5+ years.

VW (and their other brands) and BMW have good new EVs coming to market now, while Toyota is waking up too. They will survive I think. Stellantis though, not sure about them. And many Chinese carmakers will be gone too.