mkdir /etc/e-smith/templates-custom/opt/remi/php73/root/etc/php.ini/ -p
cp /etc/e-smith/templates/opt/remi/php73/root/etc/php.ini/10LanguageOptions /etc/e-smith/templates-custom/opt/remi/php73/root/etc/php.ini/
then edit the new file and add what you want in front of disable_functions =
honestly this could also been a bug to open and copy the way it is done in php-fpm contribs but for the base php and all php-scl available
/etc/e-smith/templates/etc/php-fpm.d/custom.conf/10All:php_admin_value[disable_functions] = $disabled_functions