what are your thoughts on the vitamin regiment for kids, specifically an 11 year old. Can he handle the Vitamin C, D3, and Zinc? Or should we cut what we take in half?

I should have put in OP but he has some medical issues that could possibly lead to more severe reaction than typical 11 year old.

It's your child, do what you want but I'd contact your pediatrician first before doing anything. As mentioned, your 11 year old, if not "at risk" i.e. a normal healthy 11 year old, is not at any serious risk to Covid. I would think that while it probably won't hurt them to take some extra vitamins, a children's vitamin would be more than adequate and given their age, might be hard to administer on a regular basis.

I'd send them a PM or talk to your doctor.