If you told Reagan the national debt would reach $38 trillion, would he have predicted the US dollar was still king and the US stock market set 24 new record highs year to date, with lower taxes? How much more money could he have printed without consequence for his grandchildren?
During the Reagan Administration, the national debt did triple: "the public debt rose from 26% GDP in 1980 to 41% GDP by 1988. In dollar terms, the public debt rose from $712 billion in 1980 to $2.052 trillion in 1988, a roughly three-fold increase."
A momentary diversion to correct a common confusion: the US government has various ways to fund its operations, including taxes and tariffs. It can also issue debt instruments such as Treasury Bills, Notes, and Bonds. Typically these pay interest once every six months and can be redeemed for full face value at the ends of their terms (from less than a year up to 30 years). The total amount of money represented by these debt instruments comprises the national debt (because it's money the government has obligated itself to pay investors in the future).
This is entirely different from "printing money" (which of course isn't printed; it's all electronic). When the US left the gold standard, the US dollar became a "fiat currency": "created by a central bank, authorized by government regulation to be legal tender but not backed by a precious metal, such as gold or silver, nor by any other tangible asset or commodity." Because of this, like any other national central bank, the US Federal Reserve can just create money. This was done during the Great Recession beginning in 2008 under the name "Quantitative Easing". The Federal Reserve bought back some of its debt. In effect, it just told banks: "You had X amount of government bonds. You now have cash in place of those bonds."
This doesn't add to the national debt, but it can cause inflation.
Modern Monetary Theory (which is contentious) recommends financing government mainly through money creation rather than debt or taxes. This kind of works as long as the money supply doesn't increase faster than productivity. If the money supply is expanded too quickly, inflation results, because there's more money for the same amount of goods.