javascript 特定のHTML要素の直前、親、子の要素を選択する方法

<ul class="list-wrapper1">
          <li class="list1">list1</li>
          <li class="list2">list2</li>
          <li class="list3">list3</li>
          <ul class="list-wrapper2">
               <li class="list4-1">list4-1</li>
               <li class="list4-2">list4-2</li>
               <li class="list4-3">list4-3</li>
               <ul class="list-wrapper3">
                    <li class="list5-1">list5-1</li>
                    <li class="list5-2">list5-2</li>
                    <li class="list5-3">list5-3</li>
               </ul><!-- .list-wrapper3 -->
          </ul><!-- .list-wrapper2 -->
     </ul><!-- .list-wrapper1 -->

let list = document.querySelector('li.list4-2');

list.previousElementSibling

list.nextElementSibling

list.parentElement

let parent = document.querySelector('ul .list-wrapper2');

parent.childElementCount

parent.firstElementChild

parent.lastElementChild

parent.children[2]

Array.from(parent.children);