Scale current item to 1

I wonder how to scale the current index from 1 to 0.8 when swiping to the next item. I've been building a carousel on how to make the centered item from 1 to 0.8 when the user swipes to the previous item or next item

When the user swipes into the next item the current item should slowly become from a 1 to 0.8 scaleY when it's not on the center

Only one item should have a 1 scaleY and centered item should scaleY from 1 to 0.8 every touchmove not only on touchend event

const MAIN_CONTAINER = document.querySelector('.main-container');
const CONTAINER_FLEX = document.getElementById('container-flex');

if (window.screen.width < 800) {
  MAIN_CONTAINER.style.width = `${window.screen.width}px`;
}

// Get the position when clicking the element
let touchstartX = 0;
let touchstartY = 0;

// Get the position when moving the element
let touchMoveX = 0;
let touchMoveY = 0;

let previous_move = 0;

// Get the position when leaving the element
let touchendX = 0;
let touchendY = 0;

// Swipe Detection

// Default is 1
let speed_of_swipe = 0.5;

let previous_translate_item = -305;
let current_translate = -305;
let current_index = 1;

CONTAINER_FLEX.style.transform = `translate3d(-305px, 0, 0)`;

CONTAINER_FLEX.addEventListener('touchstart', (event) => {
  touchstartX = event.touches[0].pageX;
  touchstartY = event.touches[0].pageY;

  previous_move = touchstartX;
});

CONTAINER_FLEX.addEventListener('touchmove', (event) => {
  touchMoveX = event.touches[0].pageX;
  touchMoveY = event.touches[0].pageY;

  current_translate =
    previous_translate_item + (touchMoveX - touchstartX) * speed_of_swipe;

  // if (current_index === 0 && current_translate > 20) current_translate = 20;
  // if (current_index === 2 && current_translate < -620) current_translate = -620;

  CONTAINER_FLEX.style.transition =
    'transform 0ms cubic-bezier(0.165, 0.84, 0.44, 1)';
  CONTAINER_FLEX.style.transform = `translate3d(${current_translate}px, 0, 0)`;
});

CONTAINER_FLEX.addEventListener('touchend', (event) => {
  touchendX = event.changedTouches[0].pageX;
  touchendY = event.changedTouches[0].pageY;

  let val_converter = (val) =>
    -Math.sign(val) * Math.floor((Math.abs(val) - 40) / 300 + 1);

  let move = current_translate - previous_translate_item;

  current_index += val_converter(move);

  // if (move < -345) current_index += 1;
  // if (move < -40) current_index += 1;
  // if (move > 40) current_index -= 1;
  // if (move > 345) current_index -= 1;

  // including the margin
  current_translate = current_index * -305;
  previous_translate_item = current_translate;

  CONTAINER_FLEX.style.transition =
    'transform 400ms cubic-bezier(0.165, 0.84, 0.44, 1)';
  CONTAINER_FLEX.style.transform = `translate3d(${current_translate}px, 0, 0)`;

  if (current_index > 3) {
    CONTAINER_FLEX.style.pointerEvents = 'none';
    current_index = 1;

    setTimeout(() => {
      current_translate = current_index * -305;
      previous_translate_item = current_translate;

      CONTAINER_FLEX.style.transition =
        'transform 0ms cubic-bezier(0.165, 0.84, 0.44, 1)';
      CONTAINER_FLEX.style.pointerEvents = 'auto';
      CONTAINER_FLEX.style.transform = `translate3d(${current_translate}px, 0, 0)`;
    }, 400);
  }

  if (current_index <= 0) {
    CONTAINER_FLEX.style.pointerEvents = 'none';
    current_index = 3;

    setTimeout(() => {
      current_translate = current_index * -305;
      previous_translate_item = current_translate;

      CONTAINER_FLEX.style.transition =
        'transform 0ms cubic-bezier(0.165, 0.84, 0.44, 1)';
      CONTAINER_FLEX.style.pointerEvents = 'auto';
      CONTAINER_FLEX.style.transform = `translate3d(${current_translate}px, 0, 0)`;
    }, 400);
  }

  console.log(current_index);
});

//

window.addEventListener('resize', (event) => {
  if (window.screen.width < 800) {
    MAIN_CONTAINER.style.width = `${window.screen.width}px`;
  }
});

*,
 ::before,
 ::after {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

body {
  overflow: hidden;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 100vh;
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.5;
  background-color: #131b24;
}

.main-container {
  padding: 30px 0;
  height: 300px;
  width: 910px;
  border-top: 1px solid #444;
  border-bottom: 1px solid #444;
  overflow: hidden;
  background-color: white;
}

.container-flex {
  height: 100%;
  display: flex;
  column-gap: 5px;
  transition: transform 400ms cubic-bezier(0.165, 0.84, 0.44, 1);
}

.item {
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  min-width: 300px;
  max-width: 300px;
  transform: scaleY(0.8);
}

.item h1 {
  font-size: 40px;
  color: white;
}


/* ITEMS */

.item-1 {
  background-color: #2c3e50;
}

.item-2 {
  background-color: #3498db;
}

.item-3 {
  background-color: #1abc9c;
}

<div class="main-container">
  <div class="container-flex" id="container-flex">
    <div class="item item-2">
      <h1>2</h1>
    </div>
    <div class="item item-3">
      <h1>3</h1>
    </div>
    <div class="item item-1">
      <h1>1</h1>
    </div>
    <div class="item item-2">
      <h1>2</h1>
    </div>
    <div class="item item-3">
      <h1>3</h1>
    </div>
    <div class="item item-1">
      <h1>1</h1>
    </div>
    <div class="item item-2">
      <h1>2</h1>
    </div>
  </div>
</div>

Carousel for mobile screens