I don't think more is always better, especially in the case of antioxidants. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2952083/
I'd try to use food over supplements as much as possible in this case.
For many of us, even on a high quality, nutrient dense diet, its impossible to get enough of the nutrients that our compromised bodies need just from food.
The article says that high doses of isolated antioxidants can be bad, that antioxidants in high doses can have pro-oxidant properties, and that maintaining a balance is good.
"The Antioxidant Miracle" by Lester Packer who ran the maverick antioxidant lab at UC Berkeley for many years, gives a good overview of the antioxidant network, where we need a balance of various antioxidants working together synergistically.
It's the studies that have people taking high doses of only one antioxidant that show problems - this is because the antioxidant network gets out of balance and the antioxidant in question becomes a pro-oxidant, which can start to cause damage.
That said, there are times when you want the pro-oxidant effect, like the high dose IV vitamin C which was a mainstay of my successful stage 3 cancer treatment.
Linus Pauling had discovered this, but the Mayo Clinic ran their own study and decided it didn't work. The trouble was, they used high dose ORAL vitamin C, not IV as Pauling had. Mark Levine, at NIH, subsequently found that there's a limit to what can be absorbed by the intestines, around 2g at a time, and taking more will give you diarrhea, but won't increase your blood levels.
IVC is dosed between 50-100g and it goes through a couple of conversions to make H2O2 where the extra O then "rusts" the cancer (or viruses and bacteria).
My doctor currently has me on 4g a day, for immune support, taken 2g in the morning and 2g in the afternoon. For balance, I also take alpha lipoic acid, vitamins A & E, glutathione producing nutrients, selenium, CoQ10, and I eat a lot of blue, purple & red vegetables and fruits.
So, it depends on what you're trying to do with the vitamin C...