A set of premium phones including the Galaxy S21 Ultra, Xiaomi 12 Pro, OnePlus 10 Pro, and iPhone 13 series have now been put through a battery drain test. The iPhone 13 tops the chart as is typical, but the OnePlus 10 Pro surprisingly comes in second, with 2020's Mate 40 Pro following closely.
https://www.notebookcheck.net/iPhone-13-OnePlus-10-Pro-Huawei-Mate-40-Pro-set-the-pace-in-battery-endurance-test.595193.0.html
I have a feeling such tests are set up in such a way to advantage Apple.