I know of no films made in China other than when China was the set location. Primarily US films might be in Canada because it is cheaper to emulate New York City, Chicago, or Boston specifically. If the location is set is American locations, it is normally shot in America. If the film is set in Europe, it generally is shot in Europe.
The big question is how Trump plans on doing this.
First, movie funding is varied - China funds a LOT of American made movies. Look at the production companies at the beginning of the movie carefully and you'll see a number of them are from China - Tencent, Alibaba, etc., have tons of production companies that sponsor movies. And of course, yes, the movie is content reviewed before sponsorship.
Second, what part is tariffed? There is nothing that's physically shipped around or valued. If the production company spends a week shooting in Canada, what is the "thing" you're going to tax? And how are you going to price that thing? At the very most you end up with a few hard drives that have data on it, that didn't have data on it before. And then there's the post production and other stuff.
Third, retaliation will come quick and swift, and this is a lot easier. For example, Canada might put a 100% tariff on American movies - by ticket cost. So an American movie ticket now costs double. Ticket prices at the theatre aren't cheap, and you think many people are going to pay $50 to see a movie? That is basically going to guarantee American movies bomb if they don't get much traction in Canada, or international box office receipts get down to nothing. Some movies don't make their money back without international receipts
Finally, Hollywood accounting will just screw everything up as well.
It's hard enough to determine tariffs on auto parts because they cross the border so many times (e.g., raw aluminum is mined and smelted in Canada, forged into a piston in Detroit, goes back to Windsor to be put in an engine, which goes back to Detroit to end up in an F-150.
With movies, things get complicated very quickly. Especially since many Canadian production companies shoot movies in Hollywood and vice-versa (see Lionsgate Films, who have quite a portfolio of American movies). Then there's also expertise - Vancouver is known for VFX expertise. Name any VFX company and they have offices all around the world, Vancouver included.
The final point - why is Trump trying to help Hollywood? California is a rather blue state, and Gavin Newsom isn't exactly well liked by many MAGA folks.