My new se iPhone just froze. Won’t turn on or charge

Try the steps in this Apple article:

If your iPhone won't turn on or is frozen - Apple Support

Force restart the phone:

• Press and quickly release VOLUME UP

     then

• Press and quickly release VOLUME DOWN

     then

• Hold the SIDE button until an Apple logo appears (15-30 seconds), ignoring "slide to power off" if it appears

The operative word here is QUICKLY; and try it a couple of times, the timing is a little tricky.