Application Insights customizing

Hello,

It possible to customize Cloud Watch Application Insights components? I know that I can chose metrics and logs of wich alerts will be created, but I can't find any examples of documentation of more specific customization. For example I would like to create alarm related to namespace "CWAgent", metric "disk_used_percent" and use as a dimensions "InstanceId" and specific "path" ("/" for an example). Is it possible to define thresholds in component definition? Can I generate alerts by Cloud Watch Application Insights using CloudWatch cross-account observability?

Thank from advance.

Best Regards, Łukasz Milczarski