I have noticed that my website is using three files.

https://www.example.com/index
https://www.example.com/index.html
https://www.example.com/index.php


Because of "duplications" problem, I want to redirect all these files to the main domain https://www.example.com, by using htaccess
Anyone has an idea about the code snippet that I can use it for this purpose?

Regards