New IPHONE 13 pro max taking too long time to switch on ???

Since it is still covered by warranty, I suggest that you make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> Apple – Location Selector. After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

It should take no more than 30 seconds.

Force reset it:

• Press and quickly release VOLUME UP
• Press and quickly release VOLUME DOWN
• Hold the SIDE button until an Apple logo appears (15-30 seconds), ignoring "slide to power off"

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