Sorry it's been a while since using Pro at the coalface. I've found that if you highlight the row in the table then go to 'Attributes' next to the Create Modify Delete Select tools.
In that pane you can then right click on the feature name and click 'copy attributes'.
Select the new line (create/add another row if you haven't already) then the attribute pane will update to show the newly selected row. Right-click on the feature name and click 'Paste attributes'
Apply edits in the attribute pane and save the layer edits.