HTML
Add .left or .right class together with .btn class for the direction needed.
<button type="button" class="btn left">Default left</button>
Sizes - large buttons
Add .btn-lg for a larger size.
<button type="button" class="btn btn-lg right">Default right large button</button>
Color style variant
Add .btn-primary class for primary style.
<button type="button" class="btn btn-primary left">Primary left</button>
CSS Tokens/Variables
For the overwrite tokens visit the button standard CSS Tokens, since there are the same.