This is absolutely incorrect. The debt ceiling is also about existing debt because servicing that debt is one of the government's expenditures.
Specifically:
> By hitting the limit and failing to pay interest payments to bondholders, the United States would be in default, lowering its credit rating and increasing the cost of its debt.
https://www.investopedia.com/terms/d/debt-ceiling.asp
And doing so would violate the 14th amendment which states that "The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned."
In short, in past years Congress authorized the government to spend, and in doing so drove the issuance of government bonds. By failing to increase the debt ceiling now, Congress is effectively stopping the government from paying interest on the debt previously issued to pay for those past expenditures they authorized. In effect, they ran up the credit card and now they're stopping the executive from paying the bill.