I believe with such a capacity in battery, it would guarantee a good endurance from moderate to heavy usage. Otherwise, the OnePlus 15 having a 7300mAh battery was enough, but what differentiates it is that the 16 focuses more on maximising performance. People face storage issues there might be a possibility to reduce the problem.
I think Nord CE 6 is perfectly balanced for those users who do not want to pay flagship prices and prefer reliable performance. The bigger battery will allow them to use it for longer durations without charging. I just hope that OnePlus gives it more than two major Android updates.