Sitemaps are not required for a website to be WCAG 2.1 AA compliant. However, they are often recommended when considering Success Criteria 2.4.5: Multiple Ways. This criteria requires that there is more than one way to access any page within a site (excluding the steps and/or the result of steps in a process).
Sitemaps are typically recommended and used because they provide a standard way for users to access any page within a site, aside from content that is excluded from this rule. Another option that is commonly recommended and used is a site-wide search component.
Other techniques include (but are not limited to) the following:
- Adding additional links to all relevant pages
- Providing a table of contents
- Providing a list of links to all other pages
- Linking to all pages via the home page
For step-by-step guidance in reviewing these and other WCAG requirements, check out the browser-based Manual Guided WCAG Audit Tool from Accessible Web.