<ul>
  <li>list item 1</li>
  <li class="selected">list item 2</li>
  <li class="third-item">list item 3</li>
  <li class="selected">list item 4</li>
  <li>list item 5</li>
</ul>

{
  const ex1 = $('li.third-item').nextAll()
  const ex2 = $('li.third-item').nextAll('.selected')
  
  console.log(ex1)
  console.log(ex2)
}

{
  const ex1 = Array.from(document.querySelectorAll('li.third-item'), element => {
    const elements = []
    
    while (element = element.nextElementSibling) {
      elements.push(element)
    }
    
    return elements
  }).flat()
  const ex2 = Array.from(document.querySelectorAll('li.third-item'), element => {
    const elements = []
    
    while (element = element.nextElementSibling) {
      if (element.matches('.selected')) {
        elements.push(element)
      }
    }
    
    return elements
  }).flat()
  
  console.log(ex1)
  console.log(ex2)
}