PHP flush(); not working

Some way to make PHP flush (); work, because it is only missing from my project, and natively the application is not working!

flush() is not supported. You’ll have to rely on something else.

Can I read and edit an internal .txt file, which was compiled in the application?

Yes, it’s explained here:
https://www.exeoutput.com/help/working-with-php/accessingfiles/

how can i get an early response from php? without using flush ();

That won’t be possible because our process waits for the end of the PHP script to retrieve data.