Create tcp-ip socket with LWIP library with Ethernet or WiFi connection

[federico]

ESP-IDF version is v4.0 with ESP-Ethernet-Kit as development board.

I successfully connect the ESP32 to the internet both through the WiFi and the Ethernet and I have got 2 different IP addresses which I can both Ping from my PC.
I want to create a socket with the lwip library.
How can I select the communication channel (Ethernet or WiFi) with whom I create the socket and connect with a remote server?

Thank you