<ul>
  <li><span>Длина </span><span class="s_h">3 м</span></li>
  <li><span>Ширина</span></span><span class="s_h">2 м</span></li>
  <li><span>Высота</span></span><span class="s_h">2.1 м</span></li>
  <li><span>Объем</span></span><span class="s_h">10 м3</span></li>
  <li><span>Грузоподъемность</span></span><span class="s_h">1.5 т</span></li>
</ul>

ul li{
  list-style: none;
  display: flex;
  justify-content: space-between;
  padding-bottom: 5px;
  margin-bottom: 5px;
  padding-left: 5px;
}

ul li::before {
  content: '';
  flex-grow: 1;
  order: 1;
  
  border-bottom: 1px solid black;
}



.s_h {
  height: 16px;
  overflow: hidden;
  order: 1;
}