You see the thing is that batter life improvements come from how well the chip (cpu) is designed. For exmaple
they can leave any perofrmance imporvements and focus on drain. Meaning instead of same power consumption and better performance
they do lower consumption with the same performance ratio.
Current chip in iPhone 12 already drains way more of battery life with 5G than a newer one more optimizied would. But apple had an option but skipped it for the next gen Apple iPhones.
One option is lowering footprint of components inside for a bigger battery, putting more effort into even higher optimization of apps or at least letting the user to decide what it wants more in settings, be that power or efficiency.
Also investing into new battery techonolgies would be good as well, like Tesla did for itself.
By adding more new stuff with smaller battery thats not gonna result into anything good...
Huawei for exmaple, have awesome chips, which r already few gens ahead in 5G than apple is, meaning they r selling older unoptimized tech...
If we dont look at current Huawei problems they are having like ban, security ~(cos android) and maybe even optimization, they would come off as a clear winner.
Why I said optimization is because it's always easier to put more RAM into the system rather than having apps that are efficient with RAM and are optimizied for that specific device and its components inside of it.
Here is were Apple always came up on top, less RAM, lesser power drain and even smaller footprint on curcuit board.
But what Huawei nails at is with Big and good battery, quality camera that is def. on pair with apple's.