.product_img_slide {
    padding: 100px 0 0 0;
  }

  .product_img_slide > .carousel-inner > .carousel-item {
    overflow: hidden;
    max-height: 650px;
  }

  .carousel-inner {
    position: relative;
    width: 100%;
  }

  .product_img_slide > .carousel-indicators {
    top: 0;
    left: 0;
    right: 0;
    width: 100%;
    bottom: auto;
    margin: auto;
    font-size: 0;
    cursor: e-resize;
    /* overflow-x: auto; */
    text-align: left;
    padding: 10px 5px;
    /*  overflow-y: hidden;*/
    white-space: nowrap;
    position: absolute;
  }

  .product_img_slide > .carousel-indicators li {
    padding: 0;
    width: 76px;
    height: 76px;
    margin: 0 5px;
    text-indent: 0;
    cursor: pointer;
    background: transparent;
    border: 3px solid #333331;
    -webkit-border-radius: 0;
    border-radius: 0;
    -webkit-transition: all 0.7s cubic-bezier(0.22, 0.81, 0.01, 0.99);
    transition: all 1s cubic-bezier(0.22, 0.81, 0.01, 0.99);
  }

  .product_img_slide > .carousel-indicators .active {
    width: 76px;
    border: 0;
    height: 76px;
    margin: 0 5px;
    background: transparent;
    border: 3px solid #c13c3d;
  }

  .product_img_slide > .carousel-indicators > li > img {
    display: block;
    /*width:114px;*/
    height: 76px;
  }

  .product_img_slide .carousel-inner > .carousel-item > a > img, .carousel-inner > .carousel-item > img, .img-responsive, .thumbnail a > img, .thumbnail > img {
    display: block;
    max-width: 100%;
    line-height: 1;
    margin: auto;
  }

  .product_img_slide .carousel-control-prev {
    top: 58%;
    /*left: auto;*/
    right: 76px;
    opacity: 1;
    width: 50px;
    bottom: auto;
    height: 50px;
    font-size: 50px;
    cursor: pointer;
    font-weight: 700;
    overflow: hidden;
    line-height: 50px;
    text-shadow: none;
    text-align: center;
    position: absolute;
    background: transparent;
    text-transform: uppercase;
    color: rgba(255, 255, 255, 0.6);
    -webkit-box-shadow: none;
    box-shadow: none;
    -webkit-border-radius: 0;
    border-radius: 0;
    -webkit-transition: all 0.6s cubic-bezier(0.22, 0.81, 0.01, 0.99);
    transition: all 0.6s cubic-bezier(0.22, 0.81, 0.01, 0.99);
  }

  .product_img_slide .carousel-control-next {
    top: 58%;
    left: auto;
    right: 25px;
    opacity: 1;
    width: 50px;
    bottom: auto;
    height: 50px;
    font-size: 50px;
    cursor: pointer;
    font-weight: 700;
    overflow: hidden;
    line-height: 50px;
    text-shadow: none;
    text-align: center;
    position: absolute;
    background: transparent;
    text-transform: uppercase;
    color: rgba(255, 255, 255, 0.6);
    -webkit-box-shadow: none;
    box-shadow: none;
    -webkit-border-radius: 0;
    border-radius: 0;
    -webkit-transition: all 0.6s cubic-bezier(0.22, 0.81, 0.01, 0.99);
    transition: all 0.6s cubic-bezier(0.22, 0.81, 0.01, 0.99);
  }

  .product_img_slide .carousel-control-next:hover, .product_img_slide .carousel-control-prev:hover {
    color: #c13c3d;
    background: transparent;
  }

Here is a Corousel widget that is an extension of yii\bootstrap5\Carousel, to show image thumbnails as indicators for the carousel.

Here is the widget code. <?php namespace app\widgets; use Yii; use yii\bootstrap5\Html;

class Carousel extends \yii\bootstrap5\Carousel {

public $thumbnails = [];

public function init()
{
    parent::init();     
    Html::addCssClass($this->options, ['data-bs-ride' => 'carousel']);
    if ($this->crossfade) {
        Html::addCssClass($this->options, ['animation' => 'carousel-fade']);
    }
}

public function renderIndicators(): string
{
    if ($this->showIndicators === false){
        return '';
    }
    $indicators = [];
    for ($i = 0, $count = count($this->items); $i < $count; $i++){
        $options = [
            'data' => [
                'bs-target' => '#' . $this->options['id'],
                'bs-slide-to' => $i
            ],
            'type' => 'button',
			'thumb' => $this->thumbnails[$i]['thumb']
        ];
        if ($i === 0){
            Html::addCssClass($options, ['activate' => 'active']);
            $options['aria']['current'] = 'true';
        }       
		
		 $indicators[] = Html::tag('li',Html::img($options['thumb']), $options);
    }
    return Html::tag('ol', implode("\n", $indicators), ['class' => ['carousel-indicators']]);
} }