usb hid how to send 6 bytes of data, app_usbd_hid_kbd_key_control can only send 1 key value, I see that app_usbd_hid_kbd_ctx_t can fill 6 bytes, please see
typedef struct {
app_usbd_hid_ctx_t hid_ctx; //!< HID class context.
struct app_usbd_hid_kbd_ctx_internal_s {
uint8_t modifier; //!< Keyboard modifier state @ref app_usbd_hid_kbd_modifier_t.
uint8_t reserved; //!< Reserved value.
uint8_t key_table[6]; //!< Keyboard keys table @ref app_usbd_hid_kbd_codes_t.
} rep;
uint8_t report_buff[8]; //!< Raw report buffer.
uint8_t leds_state; //!< Output report LEDs state.
uint8_t set_report; //!< Set report flag.
} app_usbd_hid_kbd_ctx_t;