At its core <multi-options> is a form control helper, designed to wrap around a list of checkboxes and a text field. It then progressively-enhances the containing UI, turning them into a tag-builder, or category field.
Think 'Select2', or 'Chosen' without the depedencies, and using modern web tech.
It allows a user to:
It is delivered as a dependency-less Web Component.
The developer has full control over the HTML and CSS, as long as the developer uses good form markup, and a key set of attributes.