JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<ul>
  <li id="menu-item-1555" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-has-children menu-item-1555">
    <a href="#" aria-expanded="false" class="">Nos métiers : Fonctions support</a>
    <ul class="sub-menu">
      <li id="menu-item-1673" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-1673">
        <a href="#">Test insertion shortcode tableau RWD – Alex</a>
      </li>
      <li id="menu-item-1600" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-1600 menu-item-has-children">
        <a href="# " aria-expanded="false" class="btnForExpanding">testu</a>

        <ul class="sub-menu">
          <li id="menu-item-1656" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-1656">
            <a href="#">Test de tableau – page – style 3 Empilement Stacking</a>
          </li>
        </ul>
      </li>
    </ul>
  </li>

  <li id="menu-item-1555" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-has-children menu-item-1555">
    <a href="#" aria-expanded="false" class="">Nos métiers : Fonctions support</a>
    <ul class="sub-menu">
      <li id="menu-item-1673" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-1673">
        <a href="#">Test insertion shortcode tableau RWD – Alex</a>
      </li>
      <li id="menu-item-1600" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-1600 menu-item-has-children">
        <a href="# " aria-expanded="false" class="btnForExpanding">testu</a>

        <ul class="sub-menu">
          <li id="menu-item-1656" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-1656">
            <a href="#">Test de tableau – page – style 3 Empilement Stacking</a>
          </li>
        </ul>
      </li>
    </ul>
  </li>
  <li id="menu-item-1555" class="menu-item...

CSS

.activu {
    font-weight: $fw-semiBold;

    &:after {
        transform: rotate(180deg);
    }
}

JavaScript

$('.menu-item-has-children > a').on('click', function(e){
    e.preventDefault();
    var EltToToggle = $(this).next('.sub-menu');
    var notToHide = $(this).parents('.menu-item').find('.sub-menu');
		
    
    $(".sub-menu").not(notToHide).hide();
    EltToToggle.fadeToggle();
    $(this).toggleClass('activu');
     return false;
  });