New iphone 13 battery draining faster than 3 yr old iphone 11

5G uses more energy than LTE or 3G, so if you are using 5G extensively it will drain the battery faster than an older phone. But a brand new phone will also use more energy for the first few days as it indexes the phone’s content.

iPhone 11 and later models, battery performance --> About the battery and performance of iPhone 11 and later