Send a value from HA to a BLE server running on ESP32 board

I’ve a BLE client that can connect to a BLE server configured on ESP 32 board:

  - mac_address: 34:94:54:xx:xx:xx
    id: itag_black

I’ve defined a BLE sensor that can read characteristic_uuid:

 - platform: ble_client
    ble_client_id: itag_black
    name: "UUID"
    service_uuid: '37fc19ab-98ca-4543-a68b-d183da78acdc'
    characteristic_uuid: 'a40d0c2e-73ba-4d8b-8eef-9a0666992e56'

The first byte is showed on the HA dashboard (in decimal):

The question is: is it possible to send a value (in exadecimal, or ASCII) to the BLE server
In the same manner that I can do, i.e., using an iPhone’s app like nRf Connect ?

Any idea?
Thanks in advance.