How do I stop my new iPhone from constantly shutting down and requiring a passcode?

Good morning having a problem with the phone just bought it yesterday. I turned the phone on with my press code number. It’s on for a few minutes shuts off. I have to put the number in again works for a while shut down. I have to put the number again. It does this constantly how do they stop there from doing it and leaving the phone on so I don’t have to re-put my press code number in

[Re-Titled by Moderator]

Original Title: Phone shutting down constantly and having to put my four digit number in all the time