How to redirect from example.com/blog to example.com/blog/index.php

My blog is working good after installing a 404 redirect page to get rid of the permalink error. here is the thread i started couple of weeks ago about the said problem:

Now its working good but when i go to example.com/blog i get a ‘page not found’ error but it’s simple to fix of course by giving all of my “home” links an index.php like “example.com/blog/index.php”.

its working good but when i installed proper pagination to make the posts paginated and click the page ‘1’ link, it directs to example.com/blog. also, the search page links will have a “example.com/blog/page/2/?s=example” instead of “example.com/blog/index.php/page/2/?s=example” that result to ‘page not found error’

so my problem is every time a user go to example.com/blog without the index.php, it results to ‘page not found error’ how can i overcome this?