First, buying a roast and putting it wide open in your fridge a few days before you cook it is not dry-aging.
While we would like to think it is dry-aging, it is more about getting moisture out and getting some enzymes to help break down the meat.
Getting the moisture out helps the beef taste like beef. On enzymes, I’m not sure if there is but the meat is definitely more tender.
To safely dry your roast, remove it from the plastic bag/covering. Add a generous amount of oil all around it. Place it on the bottom of your fridge.