Another example with less HTML.
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" />
<h5 class="card-header d-flex justify-content-between align-items-center">
Title
<button type="button" class="btn btn-sm btn-primary">Button</button>
<!-- Wrap with <div>...buttons...</div> if you have multiple buttons -->
</h5>