You could assume that the Galaxy would have it easy and just win the battery battle given that the Xiaomi 13 Pro's battery is 4,820 mAh

 Galaxy's battery is almost 4% larger at 5,000 mAh. Not so fast, as the Xiaomi's software tactics

to disable background programmes result in a battery life that is longer than you may think. 

As you can see, the phones are virtually even in terms of battery life for web browsing, 

with the Galaxy outperforming the Xiaomi in 3D gaming (perhaps due to throttling),

the Xiaomi actually holding a significant lead in terms of YouTube video playback times.

In practise, both phones can easily last through even longer days.