iPhone SE 2020 Battery Issues

I bought my iPhone SE when it was released. So it has been just slightly over a year since I had the phone. The phone's battery from the start has been extremely poor. The phone has never last me a full school day. I have to charge the phone 2-3 times just whilst I'm at school. I thought the A13 chip was supposed to be more efficient?! As you may be aware, schools don't allow people to use phones all the time so clearly I don't use the phone heavily. I have had to buy a portable because of the phone poor battery life. I have also tried everything to reduce battery usage. I have low power mode on, I try to keep my 4G and WiFi off when it's not needed. Background app refresh is off etc. iCloud back up is off but still not difference. The phone's battery is unreliable to the point where I cannot leave my house with a charger and a portable charger. My iPhone 11's battery life is amazing compared to the SE. I'm constantly charging my phone to the point where people ask if my phone is broken lol. Does anyone know how to fix this?