How to make a toggle switch from a push-button using software. Call a function in the main loop that changes the toggle variables state only when it picks up changes in the pin state. Differentiates between button press and button release.

toggleState

const int buttonPin = 5;
const int ledPin = 13;

void setup() {
  Serial.begin(9600);
  pinMode(buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);
  
  digitalWrite(ledPin, LOW);
}

void loop() {
  digitalWrite(ledPin, checkToggleState(buttonPin));
}

int state = HIGH;
int buttonState;             // the current reading from the input pin

int checkToggleState(int buttonPin){
  int reading = digitalRead(buttonPin);

    // if the button state has changed:
    if (reading != buttonState) {
      buttonState = reading;
      
      //Button went HIGH
      if (buttonState == HIGH) {
        Serial.println("Button pressed");
        state = !state;
      }
      //Button went LOW 
      else {
        Serial.println("Button released");
      }
    
  }

  return state;
}