arduino-esp32/libraries/USB/examples/SystemControl/SystemControl.ino

#include "USB.h"
#include "USBHIDSystemControl.h"
USBHIDSystemControl SystemControl;

const int buttonPin = 0;
int previousButtonState = HIGH;

void setup() {
  pinMode(buttonPin, INPUT_PULLUP);
  SystemControl.begin();
  USB.begin();
}

void loop() {
  int buttonState = digitalRead(buttonPin);
  if ((buttonState != previousButtonState) && (buttonState == LOW)) {
    SystemControl.press(SYSTEM_CONTROL_POWER_OFF);
    SystemControl.release();
  }
  previousButtonState = buttonState;
}