Correct. If there were no tariffs, you could buy a chinese EV for cheap. In this case for so cheap that the domestic US/Non-Chinese market cannot compete. So in order to protect these markets, the product needs to be made artificially more expensive with tariffs. This way, the domestic markets have a chance of competing.

However, this also isolates the country and provokes retaliation from the other side. This usually results in both sides sabotaging their trade relations with each other (for ex. with tariffs) which is called a trade war.