Any student requesting an accommodation for extended due dates, extra time on a quiz, etc. (whether on Canvas or not), should have documentation from DSS, so be sure you have checked in with their office for some additional information.
Canvas has several ways that you can accommodate students, not the least of which is the ability to create a separate due date from the rest of the class, which is covered on this page from the Canvas documentation. But there are several other areas in Canvas that will allow an instructor to create various accommodations. Many are covered in this blog post from the Canvas Community, which outlines several features with links to the appropriate faculty documentation. Though posted from an Instructional Designer's perspective, it gives some good information for faculty, as well.
Additionally, be sure to check this article, which gives an overview of all of the accessible features in Canvas--both from a faculty perspective as well as the student's perspective.