Button Border Radius Rounded buttons are possible with the border_radius prop. Demo
Twig
{% include '@bolt-elements-button/button.twig' with { content: 'This is a fully rounded button', border_radius: 'full', attributes: { type: 'button' } } only %}
HTML
<button type="button" class="e-bolt-button e-bolt-button--border-radius-full">This is a fully rounded button</button>