In this page from the MetalPopGames website, you can find a lot of (very useful!) tutorials on how to use the Unity UI Accessibility Plugin (UAP) to make the interface of your Unity based game accessible to blind and visually impaired players.
The tutorials available from the page cover a wide variety of aspects: from quick instructions to get you started, to more advanced topics such as best practices, improving behaviors, and optimizing the user experience for your users. Instructions on how to test and debug the accessibility of your game are also provided.
Note that each aspect is covered in a separate tutorial; the linked overview pages lists all of them.