When, due to some shock, the economy is operating below its potential for other than a brief period, we would expect that part of the stabilising mechanism would be that interest rates would be lower than neutral. And they would be higher than neutral when the economy was tending to overheat.
This neutral rate is not, however, an observable magnitude: there is no statistical release you can consult to find out its value. Nor, of course, are other magnitudes which are common in the lexicon of macroeconomic policy, like ‘full employment’, ‘price stability’, or ‘sustainable growth’.