HTML

button max width bootstrap

<button type="button" class="btn btn-primary btn-block">Button Name</button>

increasing the width size of button in bootstrap

<button type="button" class="btn btn-primary btn-lg btn-block">Block level button</button>
<button type="button" class="btn btn-secondary btn-lg btn-block">Block level button</button>

full width bootstrap button

class="btn btn-primary btn-block"

how to reduce the size of a button in boostrap

<button type="button" class="btn btn-primary btn-sm">Small button</button>
<button type="button" class="btn btn-secondary btn-md">Medium button</button>
<button type="button" class="btn btn-secondary btn-lg">Large button</button>

bootstrap button bigger

<button type="button" class="btn btn-primary btn-lg">Large button</button>
<button type="button" class="btn btn-secondary btn-lg">Large button</button>

bootstrap button full width

Create block level buttons—those that span the full width of a parent—by adding .btn-block.