Dimmable Switch with YYAC-3S. https://help.sinric.pro/pages/tutorials/tutorials/dimmable-switch/YYAC-3S.html

YYAC3S.ino

const int pwmPin = 16;  // 16 corresponds to GPIO16 of ESP32

// setting PWM properties
const int freq = 1000; // 1KHz
const int ledChannel = 0;
const int resolution = 8;
 
void setup(){
  ledcSetup(ledChannel, freq, resolution);
  ledcAttachPin(pwmPin, ledChannel);
}
 
void loop(){
  
   /* dutyCycle between 0 to 115 does not seems to have an any effect on the bulb. */

  // increase the brightness. 
  for(int dutyCycle = 115; dutyCycle <= 255; dutyCycle++){   
    ledcWrite(ledChannel, dutyCycle);
    delay(15);
  }

  // decrease the brightness
  for(int dutyCycle = 255; dutyCycle >= 115; dutyCycle--){
    ledcWrite(ledChannel, dutyCycle);   
    delay(15);
  } 
}