https://help.sinric.pro/pages/tutorials/switch/part-1

switch-part-1.ino

#if defined(ESP8266)
  #define relay        12
#elif defined(ESP32) 
  #define relay        16
#elif (ARDUINO_ARCH_RP2040)
  #define relay        6
#endif

void setup() {
  Serial.begin(115200);
  pinMode(relay, OUTPUT);
}

void loop() {
  Serial.println("Writing HIGH ..");
  digitalWrite(relay, HIGH);
  delay(5000); 
  
  Serial.println("Writing LOW ..");
  digitalWrite(relay, LOW);
  delay(5000);
}