Why is new iphone 16 pro max battery draing too fast!!

This is normal. When an iPhone is new the battery needs to charge a few times to reach maximum capacity. New iPhones also need to sync a lot of data and also backup to iCloud, which may require more syncing if other devices such as iPads or Macs are involved. It also needs to index all the data to speed up operations such as search. Lastly, you probably updated to iOS 18.1 which requires installing Apple Intelligence and AI is busy learning about your other apps etc. Give it a week to settle in and then let’s revisit your battery consumption.

I can appreciate it. A lot is going on in the background. Just give it a little time.