Both Canvas and Microsoft Office provide built-in tools to help you determine whether you have any accessibility issues and also fix them.
See How to use the Canvas Accessibility Checker for an illustrated guide.
See How to use the Microsoft Accessibility Checker for an illustrated guide.
In addition, other accessibility checkers are available.
WAVE Web Accessibility Evaluation Tool - A website for evaluating publicly available web pages
WAVE Browser Extensions - Tools for evaluating pages on password-protected sites such as Canvas