Physics is one of the classes where (IMO) common syllabi diverge the most from the MCAT. For physics, technically almost all of the content you'll encounter in physics 1 could show up on the MCAT, with a few weird exceptions like momentum, but the style of problem-solving emphasized in most physics classes doesn't align that well with how the MCAT tends to operate—most obviously in terms of how calculations are handled, but even beyond that, the MCAT doesn't tend to test physics in a way that depends on highly intricate problem set-ups, systems of multiple equations, and so on. Instead, most MCAT physics problems tend to involve one or two steps, and the most difficult thing is often figuring out what they're asking for exactly. The degree to which a physics class would be helpful for the MCAT or a waste of time might depend on the exact syllabus and instructor, but I'd tread carefully.
These days there's a lot of MCAT-focused materials out there, as other people have mentioned. In general I'd lean towards using MCAT-tailored resources to prep for the MCAT. Physics is one of the more extreme examples, but there are almost always some divergences between how classes tend to present the material and how the MCAT tests it, plus courses always involve time-consuming elements like exams. If you have to take a certain number of credits, that's one thing, but if not, I'd say just go for it with non-course options and only consider taking a class if you really feel like you'd seriously benefit from working through the material completely from scratch in a highly structured environment.
