Accessibility is more of a set of design guidelines to keep in mind as you work. If your document is image-heavy, contains forms, or contains links, you will need to do different things. What I’m saying is that there isn’t a template for accessibility in the same way that there isn’t a template for ‘legible text’.
Again, this can be done with a Timeline property. There are filters for “Contrast”, “Hue” and “Saturation”, which could be used to adjust the coloring of elements. By dropping the saturation to zero, and increasing the contrast, that could improve the view.
Yet, it is interesting to think about what could be done with Hype to make life easier for people with disabilities. Large text, high contrast, voice over… this might be a good idea for a template. But if the settings are changed after the page is loaded, it probably wouldn’t pass an automated accessibility check.