iPhone 16 shutting down

I got the new iPhone the day they came out and it has randomly shut down without warning. The first time was while texting. I wasn’t on WiFi or plugged in, thought it was just an update. Has happened twice since then and another time today. Today I was answering a call and it went black. No idea what’s happening. Can someone advise? Is it the phone? Something I’ve done? Wasn’t low battery or too hot.