Use Bootstrap’s custom button styles for actions in forms, dialogs, and more with support for multiple sizes, states, and more.
Check out Documentation
use .disabled in class .btn class to get Disabled button
use .btn-lg in class .btn class to get Large button
use .btn-sm in class .btn class to get Small button
use .btn-group-lg in class .btn-group class to get Large size button group
this is default size
use .btn-group-sm in class .btn-group class to get Small size button group