Reduction of the BLE transmitting power possible on ESP32?

Is it possible to reduce the BLE transmitting power of the ESP32 by software?

Google leads here, which refers to esp_bt.h in the IDF, where I’ve found this function:

 * @brief  Set BLE TX power
 *         Connection Tx power should only be set after connection created.
 * @param  power_type : The type of which tx power, could set Advertising/Connection/Default and etc
 * @param  power_level: Power level(index) corresponding to absolute value(dbm)
 * @return              ESP_OK - success, other - failed
esp_err_t esp_ble_tx_power_set(esp_ble_power_type_t power_type, esp_power_level_t power_level);

So the generic answer is ‘yes’, but that depends on whether or not the default setting (which seems to be +3dBm if I followed comments right) is higher than what you want to set…
The available power levels are right here
I guess you will use ESP_BLE_PWR_TYPE_DEFAULTfor power_type, but those are defined just right above the power levels.