Based on my knowledge, there is no in built way to set up an alert in case if the pipeline didnt get triggered (even though it was scheduled for)
You can set up alerts for success or failure.
In case if you want to receive alerts in case of pipeline not getting triggered, you would have to have a custom logic at the destination end
Eg : lets say your sink gets refreshed at 7pm everyday, you can add a logic at sink end to check the status of refresh and if refresh is not done; then validate the pipeline run history and notify