Hi Joel.
What exactly do you mean by “integrate ESP32 in existing switchboard”?
Regards,
Sara

I mean integrating esp32 in existing wall switchboards.If we lose power to esp32 then whole circuit will shot down right?

It depends on what the ESP32 is doing and how it is connected.
If the ESP32 is executing something, and it loses power, it will stop doing whatever it is doing and will not work as expected.

I’m not really sure what the ESP32 will be doing on the switchboard.

suppose esp32 suddenly loses power then all devices connected to it become OFF.Light/fan cant be operated unless esp32 have power.How do we resolve that?

Yes.
If you are controlling those devices with the ESP32, and the ESP32 loses power, those devices will stop working.
I don’t know a workaround for that issue.