Screen magnifiers and other assistive technologies can be kind of
Good news! This guideline shouldn't require a lot of work on your part. When authoring your site, just make sure that the content doesn't hamper user agent support for resizing text, including text-based controls. However, be aware that if you're utilizing user agent technology that doesn't furnish such support, then it's your job to provide help for resizing text or changing the layout. For example, you could use server-side script that someone looking at your site could use to assign different style sheets.
There are some exceptions to this rule. You don't need to worry about resizing for captions or images that themselves display text. In addition, it's okay if your site includes truncated text as long as you provide users with a way to access the full version. A good example of this is in email service providers where long subject lines are cut off rather than wrapped around.