Yes, the content and formatting design of a full size website will shape-shift automatically to fit the screen-size of a mobile device or tablet. The text, borders, etc are pre-designed to break at specific dimensional collapse points.
Yes, WCAG 2.1. The platform is Accessibility Compliant, however the content that a site-owner puts on his or her OpenScholar website, we cannot vouch for its compliance (for example, no document in a PDF format will be Accessibility Compliant). We can, however, encourage site owners to use certain AC tools like Site Improve that flags elements within the site that are not in compliance.