If it's to damage China's EV producers, then yes, they'll work.
If it's to promote sales of domestically produced EVs, then probably a bit, although to what degree is unknown.
If it's to help domestic producers ramp up and grow the domestic EV market at, or around, the same rates that cheap imported EVs would... probably not.
Which circles back to, if the goal is to dampen and slow the adoption of EVs en masse, then yes, it will probably work. Although, to what degree is unknown and can be heavily influenced by other forms of legislation and regulation.