Food is always better.
As to experiments to perform, you would need an animal that does not produce vitamin C which is only humans and very few large mammals. Would not recommend making a human vitamin C deficient as our immune system depends on vitamin C. Don’t have any suggestions on how to prove that food vitamin C is better than supplement vitamin C since both will deliver vitamin C in an active form. Problem is the human organism lives so long that nutrient impacts like sources of nutrients (food vs supplements) would be difficult to prove in a short time.
Would recommend you do a PubMed (medical literature) search for “vitamin C sources” and look for studies that considered vitamin C sources. Perhaps you would get some experiment ideas there.