This doesn’t follow, for all kinds of reasons.
First, the use of the word “debt” implies an analogy to the kind of debt we are familiar with in our personal lives, but national debt isn’t like that. For a large western economy, like the US, it’s more like a closed system. So “debt” in this context actually just refers to an expansion of the money supply. Expanding the money supply might be good or bad, but you can’t just say that its historic expansion should be limited by some arbitrary referral to GDP.
Second, GDP is an annual measure of output, whereas debt is a static measure of something in total. Why is there a problem with the former being 120% of the latter? Even if you use the terrible household budget analogy, you should know that many people have mortgages worth 4 times their annual income. If 400% is OK for an individual, why is 120% bad for a country?
Third, GDP is a terrible measure of productivity anyway. You can increase GDP by having terrible, inefficient public services that need constant repair. You can increase it by turning a blind eye to black market activities such as corruption. It doesn’t necessarily have anything to do with fiscal revenue, which is what actually services debt.
Fourth, it ignore inflation. Debt of 120% GDP will become debt of 100% of GDP after a few years of inflation at 10%.
That’s all just objections on the grounds of economics, before we even get into any of the actual politics of the situation.