Would it be better to take AP Art History, a class that has no relation to what I wish to pursue in college, or a science course that isn't an AP but I would use in the future with my career?
(I'm trying to pursue something in the STEM field, maybe cellular biology)
I would pick a regular STEM course. Though AP Art History may help your GPA, GPA is not standarised and most colleges redo their GPAs based on the individual grades you get from the class.
If you're trying to apply to a state school requiring just the GPA, it may help to take AP Art History. Some of your science courses may require a higher GPA to reach the threshold for your school.
For the more selective schools using holistic application, it's better to take a regular STEM course that you can use for your future career. It shows colleges interest in your major.
To keep this community safe and supportive: