Bootstrap setting height for btn-block buttons

The simple & best solution would be to add top and bottom padding.

.btn-block {
    padding: 10% 0; 
    /* define values in pixels / Percentage or em. whatever suits 
       your requirements */
}

Actually, just use py-4 as an extra class on your button.

py-# adds padding on top and bottom at the same time, and you can choose how much by changing the number (I think the max is 4, but I might be wrong).

You can check all the options here (it works at least from Bootstrap 4 onwards).

Use Bootstrap padding property p-. Documentation

<a class="btn btn-default btn-block p-3" href="#">1</a>