Do existing national debt payments and potential higher interest rates for future borrowing have an equilibrium? I mean obviously the former helps keep the latt

Do existing national debt payments and potential higher interest rates for future borrowing have an equilibrium? I mean obviously the former helps keep the latter at bay, but can you really say they are in balance and that it wouldn't be better to simply default on the debt and then borrow less in future? I suppose if more countries got serious about cancelling the debt, there would also start to be talk from charities/activists of guaranteeing future rates.