Would be the command to list the system status, where I can see the notifications value. I cannot add a "notifications_enabled" in there to get just this value without getting an API error so it makes me think this functionality is not in the Nagios xi API.
Is this true? Is editing the file still the best way?
You can look into sending a core command with the API.
https://[Your xi IP address or destination]/nagiosxi/help/api-system-reference.php#system-core-command