How to set vertical padding between d-flex objects?

Question

Bootstrap

Three objects in d-flex

<div class="d-flex flex-wrap">
<a href=""
 class="btn btn-sm btn-primary mr-2" type="button">a
</a>
<button>d</button>
<button>s</button>
</div>

you need to put a vertical indent between the buttons. I can’t apply markup to the objects themselves (a component with different display in different places), only div in the example. Is there some class like my-items-3 and everything will work?