That depends on the server you're using, what panel you may be using etc.
If mlocate is installed: cmd: updatedb then run locate php-fpm.conf
or
find / -name php-fpm.conf -print
If this is cpanel, it controls php-fpm differently as well as plesk doing its thing.
--------------- Added [DATE]1550353986[/DATE] at [TIME]1550353986[/TIME] ---------------
[root@server src]# httpd -t -D DUMP_MODULES | grep mpm
mpm_prefork_module (shared)
|