Bootstrap CSS class .dropdown-toggle-split

<div class="btn-group">
    <button type="button" class="btn btn-danger">Action</button>
    <button type="button" class="btn btn-danger dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false">
        <span class="visually-hidden">Toggle Dropdown</span>
    </button>
    <ul class="dropdown-menu" aria-labelledby="dropdownMenuButton">
        <li><a class="dropdown-item" href="#">Option 1</a></li>
        <li><a class="dropdown-item" href="#">Option 2</a></li>
        <li><a class="dropdown-item" href="#">Option 3</a></li>
    </ul>
</div>