Battery life iPhone 12

I have just purchased an iPhone 12 and don’t understand why the battery is draining so quickly even when idle. I charged the phone last night 100% and this morning it went down to 61% and I hadn’t even used it. I don’t do FB or Instagram just messages and emails mostly. Browse internet but connected to home WiFi. My previous phone was an iPhone XR and the battery lasted for ever. Thinking of sending my iPhone 12 back as I don’t like it or understand why the battery drains down for doing nothing!