Controlling 3 loads using push button

So you want to toggle the loads? (I.e. one press = on, second press = off.)
Then you need to debounce the pushbuttons, and remember the previous states in order to detect the falling edges:

class PushButton {
  public:
    PushButton(uint8_t pin) // Constructor (executes when a PushButton object is created)
      : pin(pin) { // remember the push button pin
      pinMode(pin, INPUT_PULLUP); // enable the internal pull-up resistor
    };
    bool isFalling() // read the button state check if the button has been pressed, debounce the button as well
    {
      bool falling = false;
      bool state = digitalRead(pin);               // read the button's state
      int8_t stateChange = state - previousState;  // calculate the state change since last time

      if (stateChange == fallingEdge) { // If the button is pressed (went from high to low)
        if (millis() - previousBounceTime > debounceTime) { // check if the time since the last bounce is higher than the threshold
          falling = true; // the button is pressed
        }
      }
      if (stateChange == risingEdge) { // if the button is released or bounces
        previousBounceTime = millis(); // remember when this happened
      }

      previousState = state; // remember the current state
      return falling; // return true if the button was pressed and didn't bounce
    };
  private:
    uint8_t pin;
    bool previousState = HIGH;
    unsigned long previousBounceTime = 0;

    const unsigned long debounceTime = 25;
    const int8_t risingEdge = HIGH - LOW;
    const int8_t fallingEdge = LOW - HIGH;
};

const uint8_t ledPin_A = 2;
const uint8_t ledPin_B = 3;
const uint8_t ledPin_C = 4;

PushButton button_A = {  9 };
PushButton button_B = { 10 };
PushButton button_C = { 11 };

void setup() {
  pinMode(ledPin_A, OUTPUT);  
  pinMode(ledPin_B, OUTPUT);  
  pinMode(ledPin_C, OUTPUT);  
}

void loop() {
  static bool ledState_A = false;
  static bool ledState_B = false;
  static bool ledState_C = false;

  if (button_A.isFalling()) {
    ledState_A = !ledState_A;  // Toggle the LED state
    digitalWrite(ledPin_A, ledState_A);  // Write the state to the pin
  }
  if (button_B.isFalling()) {
    ledState_B = !ledState_B;
    digitalWrite(ledPin_B, ledState_B);
  }
  if (button_C.isFalling()) {
    ledState_C = !ledState_C;
    digitalWrite(ledPin_C, ledState_C);
  }
}

Pieter