I think OP means that Android Phones with comparable battery life to an iOS device tend to have a larger battery to support that (when compared to the iPhone), which is more difficult with smaller enclosures (i.e. in a large phone it's easier to hide a large battery, and they don't scale entirely proportionally to screen size).
i.e. the Pixel 5 will last about 10% longer than an iPhone 12 on a single charge, but it achieves this with a battery that is about 45% bigger (2,800 mAh vs 4,080mAh). Both have the same size screen (in fact, the iPhone is slightly larger).