Want to know about device bridging is it still useable in new blynk

No, Bridge isn’t available in Blynk IoT, but you can use Automations to send data from one device to another (although there are some restrictions/drawbacks to this approach) or you can use the HTTP(S) API to simulate Bridge, provided you are using an appropriate type of device.

There are some examples of how to do this:

For the ESP32:

For the ESP8266:

Pete.