Hello and welcome to the forum!
Please review this post on how to request help: How to get help on the Dynamo forums - FAQ - Dynamo
I’m not aware of any nodes that already do this. You would have to use Python and the API to get the schedule table data, check whether each circuit is existing or new, and then use the SetCellStyle method based on those results. But this means you can automate the whole process and wouldn’t have to manually override in the first place. It’s not the most beginner-friendly problem though. If you’re new to Dynamo, I suggest you work through the Dynamo Primer and look into Python and the Revit API.
PanelScheduleView Members
GetTableData Method
GetSectionData Method (Int32)
SetCellStyle Method (Int32, Int32, TableCellStyle)