Any sensible American should be in support of toppling Iran, the real questions to ask are "do they support a war powers act to restrict Trump's invasion plans" and also "should the USA support Israel invading Iran".
IMO the answers should be Yes for one and No for two.
You could also ask them "do you support the shah royalist faction" but I feel like 8 out of 10 Americans would just say somehting along the lines of "the what...?"