All settings and plugins presented here do not solve any accessibilty problem on a website. To make a website accessible, you need a correct semantic HTML structure and good CSS. Joomla Core uses accessible structures in the various views, such as correct labels (label) and input fields (input, select) in forms.
When a third-party template is used, one should be aware that the original structure of the views may be changed by overrides. A nice template can affect the accessibility of a website if the color contrast is not good or when elements are not accessible with the keyboard.
Accessibility has many facets, and plugins are just a help for visitors who use a (your) website in a different way than yourself.