Iphone 15pro max black screen issue

I bought iphone 15 pro max on 6th December 2023, and experiencing black screen issue

I could feel the vibrations and sounds but screen was black than i tried this

Press and quickly release the volume up button.

Press and quickly release the volume down button.

Press and hold the side button.

When the Apple logo appears, release the side button

but it did not work out waited for 10 minutes and tapped on back side and screen appears but why this happened even i do travel alone and what if this would have happened during travel this is so scary even when i tried press and hold volume button down and up flash light and siren was on.