iPhone 12 battery drains faster than expected.

I have bought iPhone 12 just 2 days back and its battery is draining was sooner than whats expected it to be. As soon I start using it keeps on daring way faster like 10% in 20 minutes on normal usage of web surfing. I even updated it to the latest iOS version and tried restarting the device. Any help would be very much appreciated. And FYI I also tried background app refresh off, switching to manual push on mails and even the mobile carrier from automatic to dedicated sim/operator name.