get

string public static
\Bitrix\Main\Config\Option::get(
 string $moduleId,
 string $name,
 string $default = "",
 boolean|string $siteId = false
);

This static method returns parameter value.

Parameter	Description	Version
$moduleId	Module ID. Required.
$name	Parameter name. Required.
$default	Returns default value, when the value is not specified.
$siteId	Site ID, when parameter value varies for different sites.

Parameter	Description	Version
$moduleId	Module ID. Required.
$name	Parameter name. Required.
$default	Returns default value, if value is not set. Default value. When default_value is not set, sources the value from array with name ${module_id."_default_option"} specified in the file /bitrix/modules/module_id/default_option.php.
$siteId	site ID when parameter value is different for various sites.

$size = Option::get("main", "max_file_size");