USB_HID_Cut_Copy_Paste.ino

/* Arduino USB Keyboard HID demo
 * Cut/Copy/Paste Keys
 */

#define KEY_LEFT_CTRL	0x01
#define KEY_LEFT_SHIFT	0x02
#define KEY_RIGHT_CTRL	0x10
#define KEY_RIGHT_SHIFT	0x20

uint8_t buf[8] = { 
  0 }; 	/* Keyboard report buffer */

#define PIN_COPY 5
#define PIN_CUT 6
#define PIN_PASTE 7

int state = 1;

void setup() 
{
  Serial.begin(9600);

  pinMode(PIN_COPY, INPUT);
  pinMode(PIN_CUT, INPUT);
  pinMode(PIN_PASTE, INPUT);
  // Enable internal pull-ups
  digitalWrite(PIN_COPY, 1); 
  digitalWrite(PIN_CUT, 1);
  digitalWrite(PIN_PASTE, 1); 

  delay(200);
}

void loop() 
{
  state = digitalRead(PIN_CUT);
  if (state != 1) {
    buf[0] = KEY_LEFT_CTRL; 	// Ctrl
    buf[2] = 27;    // Letter X
    // buf[2] = 123;	  // Cut key: Less portable
    Serial.write(buf, 8);	// Ssend keypress
    releaseKey();
  } 

  state = digitalRead(PIN_COPY);
  if (state != 1) {
    buf[0] = KEY_LEFT_CTRL; 	// Ctrl
    buf[2] = 6;    // Letter C
    // buf[2] = 124;	  // Copy key: Less portable
    Serial.write(buf, 8);	// Send keypress
    releaseKey();
  } 

  state = digitalRead(PIN_PASTE);
  if (state != 1) {
    buf[0] = KEY_LEFT_CTRL; 	// Ctrl
    buf[2] = 25;    // Letter V
    // buf[2] = 125;	  // Paste key: Less portable
    Serial.write(buf, 8);	// Send keypress
    releaseKey();
  } 
}

void releaseKey() 
{
  buf[0] = 0;
  buf[2] = 0;
  Serial.write(buf, 8);	// Release key  
  delay(500);
}

you can look at this https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf&ved=2ahUKEwj2yN2ItvzhAhWN_XMBHUtGAb4QFjAAegQICBAC&usg=AOvVaw37jTa_X9_oNnwzAFuWxTDL in page 53