One week old iPhone 14 draining battery

I don’t see anything unusual about a battery dropping by 40% over the course of a day. If anything, that is much better than the average for an iPhone.

The absolute best way to get maximum use on a charge, as well as slow the decline of battery capacity long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight, every night. The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern. If you enable iCloud Backup (Settings/[your name]/iCloud - iCloud Backup) the phone will back up overnight also, assuring that you can never lose more than the current day’s updates. Here's more information→About Optimized Battery Charging on your iPhone - Apple Support

Again, that looks perfectly normal. If you charge overnight, every night, and the phone’s battery still has at least 20% left at the end of the day the phone working normally.