Setup ESP32 for Arduino

• Start Arduino IDE and open the Preferences window.
• Enter https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json (opens in a new tab) into the Additional Board Manager URLs field.
• Open Boards Manager from Tools > Board menu and find esp32 platform.
• Select the version you need from a drop-down box.
• Click the install button.

After this choose the right board in your board manager.

• From Tools > Board menu select the right board or install it.

To read more about it click here (opens in a new tab).