how to add class to paginate button?

Good afternoon,
I am starting with datatables and I have this doubt that I cannot solve, I want to add the class "btn btn-sm btn-dark" to the paging buttons and the filter textbox, specifically the following lines:

<input type="search" class="form-control form-control-sm" placeholder="" aria-controls="datatable">

<a href="#" aria-controls="datatable" data-dt-idx="0" tabindex="0" class="page-link">Previous</a>
<a href="#" aria-controls="datatable" data-dt-idx="1" tabindex="0" class="page-link">1</a>
<a href="#" aria-controls="datatable" data-dt-idx="2" tabindex="0" class="page-link">2</a>
<a href="#" aria-controls="datatable" data-dt-idx="3" tabindex="0" class="page-link">Next</a>

attached image:

Regards,
Yon.