Is it safe to give 2 years old child supplement?

I'm about to give my daughter vitamin C from Champs and Scotts gummies that contain vitamin D and support in DHA. I've survey other brand too like Appeton etc. Some of the supplement label at the back shows age suitability differently like 2/3/5 years old above. Is it about the size of chewy tablet/pastil or the dose of vitamin contain in each tablet/pastil itself?