Ringtone going low when phone rings
Why does my ringtone go low after a few seconds after it starts ringing?
iPhone 14 Pro Max
It I designed to lower the volume as soon as it recognizes that you have heard it. If you want to turn that feature off, go to Settings > Face ID & Passcode and turn Attention Aware Features off. Also see: Turn Attention Aware features on or off on your iPhone or iPad Pro - Apple Support