// Accordion by WebSensePro.com
$(function() {
	// (Optional) Active an item if it has the class "is-active"	
	$(".accordion > .accordion-item.is-active").children(".accordion-panel").slideDown();
	
	$(".accordion > .accordion-item").click(function() {
		// Cancel the siblings
		$(this).siblings(".accordion-item").removeClass("is-active").children(".accordion-panel").slideUp();
		// Toggle the item
		$(this).toggleClass("is-active").children(".accordion-panel").slideToggle("ease-out");
	});
});

<ul class="accordion">
<li class="accordion-item is-active">
<h3 class="accordion-thumb">{{ product.metafields.my_fields.first_tab_title }}</h3>
<p class="accordion-panel">{{ product.metafields.my_fields.first_tab_description }}</p>
</li>
<li class="accordion-item">
<h3 class="accordion-thumb">{{ product.metafields.my_fields.second_tab_title }}</h3>
<p class="accordion-panel">{{ product.metafields.my_fields.second_tab_description }}</p>
</li>
<li class="accordion-item">
<h3 class="accordion-thumb">{{ product.metafields.my_fields.third_tab_title }}</h3>
<p class="accordion-panel">{{ product.metafields.my_fields.third_tab_description }}</p>
</li>
</ul>

/* Accordion CSS Code by WebSensePro.com 
https://websensepro.com/blog/how-to-create-collapsible-accordion-for-product-description-shopify/
*/
.accordion {
	 margin: 1rem 0;
	 padding: 0;
	 list-style: none;
	 border-top: 1px solid #e5e5e5;
}
 .accordion-item {
	 border-bottom: 1px solid #e5e5e5;
   list-style: none !important; 
}
/* Thumb */
 .accordion-thumb {
	 margin: 0;
	 padding: 0.8rem 0;
	 cursor: pointer;
	 font-weight: normal;
}
 .accordion-thumb::before {
	 content: '';
	 display: inline-block;
	 height: 7px;
	 width: 7px;
	 margin-right: 1rem;
	 margin-left: 0.5rem;
	 vertical-align: middle;
	 border-right: 1px solid;
	 border-bottom: 1px solid;
	 transform: rotate(-45deg);
	 transition: transform 0.2s ease-out;
}
/* Panel */
 .accordion-panel {
	 margin: 0;
	 padding-bottom: 0.8rem;
	 display: none;
}
/* Active */
 .accordion-item.is-active .accordion-thumb::before {
	 transform: rotate(45deg);
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

.accordion {
  background-color: #fff;
  color: #424242;
  cursor: pointer;
  padding: 18px;
  width: 100%;
  border: none;
  text-align: left;
  outline: none;
  font-size: 20px;
  transition: 0.4s;
}

.active, .accordion:hover {
  background-color: #868686;
}

.accordion:after {
  content: '\002B';
  color: #777;
  font-weight: bold;
  float: right;
  margin-left: 5px;
}

.active:after {
  content: '\2212';
}

.panel {
  padding: 0 18px;
  background-color: #fcfcfc;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.2s ease-out;
}