Taking rigorous classes in high school?

Hi everyone,
I am a junior high school who is currently enrolled in a one science magnet class offered in my high school (cell physiology). Since I have never taken any magnet class before I found it very difficult and hard to get used to the lots of work they give. I was thinking of dropping out of this class but heard that colleges want to see if Students have challenged themselves by taking different rigorous classes even if they get lower grades in them. Now I’m not really sure if I should drop this class and get into another easier class Or stay whatever grade I will get. Anyone’s advice about taking rigorous classes?