My iPhone is completely unresponsive

See these instructions to perform a "forced" restart of your iPhone 13:

Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the side (power) button. Only when the Apple logo appears (it might take 10-20 seconds), release that button (ignore all other screens that might appear, the one with the "slider" to turn the device off included).

If the issue persists, contact Apple Support, using this link:--> Get Support

Regards

Giulio

Perhaps you could try a 'Force Restart' just in case iPhone has lapsed into a coma(?)

 • Force restart iPhone› guide › iphone › force-restart-iphone-iph8903c3ee6 › ios

[Force restart iPhone - Apple Support]

Maybe iPhone hadn't been fully charged; now his battery may be near flat-line?

Use the USB AC adapter and Lightning cable to charge iPhone. Let it Charge at

least One Hour. ~ If the iPhone has not shown evidence of charging, try another

compatible iPhone USB power adapter with correct cable. (Be sure charge port

is clean and nothing stuck inside; also it should be Dry without moisture, etc.)

• How to Fix an iPhone That Won't Turn On | howtogeek.com (Feb 2022)

https://www.howtogeek.com/774659/how-to-fix-an-iphone-that-wont-turn-on/

• iPhone 11 Won't Turn On? Here's The Real Fix! | upphone.com (7-steps/Sept 2019)

https://www.upphone.com/fix/iphone/power/iphone-11-wont-turn-on-fix/

Following was found at Nektony.com Top 5 Reasons your iPhone won't Turn On

"As another option, you can launch iTunes on a computer and connect

your iPhone to it via a working cable. If the computer detects your iPhone,

you will see its charging status next to the name of your iPhone."

"If your iPhone is charging but won’t turn on, this could be due to one of

the reasons listed below.If your iPhone did not start charging, the problem

may be with the battery. Do not try to replace the battery by yourself. Ask

for help in Apple Support or at the nearest Apple Store.."

(The nektony site has way much involved for casual use: Tries to load junk.)

So there are several ideas out there:

Apple Support iPhone articles? Best.

• iPhone User Guide (Table of Contents) - Apple Support

//support.apple.com/guide/iphone/toc

My pleasure :)