"If World War III were to occur between NATO and let's say BRICS who would win? Why?"

It doesn't work anymore like this. Such scenario would end life on earth due to nuclear capabilities. That's the reason some scholars claim that nuclear power is all that's keeping us from a WW3.

https://en.wikipedia.org/wiki/Mutual_assured_destruction

@Master Yeet the question referred to "World War III", not Cold War, which is arguably still ongoing.

@Master Yeet if you think WW3 can happen without nuclear intervention, you're optimistic my friend.

@Master Yeet Please read the Wikipedia article I posted:
"In 1949, after the unleashing of nuclear weaponry at the end of WWII, physicist Albert Einstein suggested that any outcome of a possible WWIII would be so dire as to revert mankind back to the Stone Age. When asked by journalist Alfred Werner, what types of weapons Einstein believed World War III might be fought with, Einstein warned, "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones""

@Master Yeet My nationalist friend, if you think that WW3 would prove anything other than human ignorance, you're deeply delusional.