Can i get an executive physical exam at 20 years old if i feel like it would help me and could i also get scans to be on the safe side even if im healthy could i also get a physical exam twice a year if i ask my doctor?

Imaging is usually done based on guidelines either for prevention an/or diagnosis. Not sure what your understanding is about executive physicals, such exams can be as expensive as 25000, available at institutions, such as Cleveland Clinic or Mayo Clinic for example.

Are you ready to pay 10-20 K up front for all of it? Insurance companies have set limits for how often and what testing will be covered. If you have health anxiety consider finding a life coach/therapist to explore the reasons/learn relaxation & stress management. Health anxiety often masks unresolved internal strife. Do that work to find out why. Better investment.