I know for sure I want to major in theatre/acting and probably with a minor in filmmaking, but I may also want to major in chemical engineering. I wanted to know if this is doable and if any university would allow me to do these two major (because they are so completely unrelated).
It depends on the school. Nevertheless, it may be very overwhelming to have one engineering major plus another non-engineering major and a minor. I know several students with double major in music performance and engineering though.
Even if a school allows it, you will not be able to complete all of the courses required for both majors (and the minor) in 4 years. There is 0 overlap between those two majors and you would have no room for taking extraneous classes that interest you.