This project demonstrates how to use ESP-NOW to send messages to other ESP devices without using WiFi.
You can find an overview of ESP-NOW here.
And detailed documentation here.
The code has been written using platform.ide, but you it will work equally well in the Arduino IDE.
For the broadcast example just push the sketch to a couple of ESP32 devices. You should see that pushing the "boot" button on one of the devices turns the LED on and off on both devices.
To set up peer-to-peer communication make a note of the MAC address of one of the devices and use that instead of the broadcast address.