I mean a normal diet in the sense of “norms.”
And no, most supplements are not formulated to bring average deficiencies up to 100% of the DV for some average-size person.
Must supplements are formulated to add to the diet things that are associated with positive health outcomes. Sometimes, this means bringing up the level of something that’s commonly deficient. In other case, this means providing higher-than-minimal levels of something that’s helpful (for these nutrients, the DV or the RDA is seen as a minimum level, not an optimum level.)
Some supplements are designed as “nutritional insurance” in that they provide 100% of many nutrients, the idea being that no matter what you eat that day, whatever is missing is provide by the multivitamin. Your basic Centrum is like that - but it provide 100% of a large number of nutrients. They can’t be assuming that people get, on average, 0% of these nutrients.
But most supplements provide higher levels of various nutrients, including the most popular single multi, Centrum Silver - which provides 167% of Vitamin E and 417% of B12.
You’ll find that most multis provide more of particular nutrients… you’ll also find that the nutrients that are problematic if taken in large quantities are kept low in multivitamin formulas - for example, manganese is never amped up, and iron often very low, or not included at all.
Other nutrients are kept low because we need so much and they are very bulky - for example, calcium. Even Centrum Silver only provides 22% of the DV for calcium, yet it contains 220 mg of the stuff - more than any other ingredient. It may even be more than all the other elements, put together.