Battery life is not good

Ok, I'm sure this gets asked some, but I couldn't find a specific answer to what I'm wondering about. I just got this iPhone 11 3 days ago. Today I have less than 3 hrs of screen on time and my battery is sitting at 60%. That seems like the battery is lower than it should be no? I got this phone because all the tech reviews said I could average 15 hours + before I needed to charge and it doesn't seem my phone will go that far if after only 3 hours it has drained 40%. I don't have any social media on my phone, minus Facebook, but I'm never on it. I mainly just take pictures and listen to music through Apple Music. I'm just curious what could be causing my battery to drain so much in so little time. I realize how difficult this may be to answer without actually seeing the device, but perhaps someone can help shed some light on this.