Yes, surely you can override or specify PHP INI directives.

There are two ways to go about it

1. From within N99panel, under a VHost/Website, click on the edit icon against the label ‘Apply Custom PHP INI Settings’ . In the subsequent form place each INI directive on a separate line, and then click ‘Apply INI Settings’ . Upon a successful submission, the FPM w.r.t. the VHost/website would be restarted and the new directives should be applicable provided they are semantically and technically correct. For a list of valid PHP INI directives, please follow this link : https://www.php.net/manual/en/ini.list.php . This feature does not work if custom PHP is choosen.
2. The custom PHP directives can also be set on per dir basis by using a .user.ini files . The directives set using this method, apply only to that particular directory and do not apply to the full directory tree. As mentioned above, each directive has to be placed in a separate line. Based on the type of directive, many master directives can be overridden with a corresponding entry in the .user.ini file.