您想要这样的东西吗？

let btn = document.getElementById("toggle");
let alert = document.getElementById("alert")

 
btn.addEventListener("click", function(){
alert.classList.toggle("show")
})

.btn {
  padding: 0.5rem 1rem;
  border: none;
  background-color: #4e4e4e14;
  color: #003cff;
  border-radius: .5rem;
  font-weight: bold;
  cursor:pointer;
}

.alert {
  display: none;
  border-radius: .5rem;
  margin-top: 1rem;
  padding: .9rem;
  border: 1px solid gray;
  background: #4e4e4e14;
}
.show{
  display:block;
}

<button class="btn " id="toggle">Toogle</button>

 <div class="alert" id="alert">
   <p>
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   </p>
 </div>