Sample php.ini can be found from a lot of places:
I just download the php 72 source code,
Code:
wget http://php.net/distributions/php-7.2.8.tar.gz
unpack it and you will find php.ini-production there.
Alternatively, you can dwonload from
https://github.com/php/php-src/blob/PHP-7.2.9/php.ini-production
but the question is, why donot you just use apt-get? it is much easier.