Brand new iPhone with poor battery life

I bought a brand new iPhone SE 2020 from my network provider two days ago. I upgraded my phone due to my previous one running slower and it’s battery life has declined over the years. So when buying my brand new phone I was shocked to notice that it also declines rather quickly. By this I mean it can’t last a whole day without charging it or giving it a boost of charge. Usually brand new iPhones tend to have a sufficient amount of battery life in them. How do I get this sorted and is there a problem here?