You could use the "Select By Location" tool to select features in the layer that intersect with other features in the same layer, then check the box to invert the selection clause.
Have a look at this solution -- same problem but on a pipe network.
https://community.esri.com/t5/arcgis-pro-questions/network-topology-errors/m-p/1412516#M82125
I just submitted an Idea for this: https://community.esri.com/t5/arcgis-pro-ideas/find-orphan-lines/idi-p/1499910
If you agree with this idea, give it a Kudo - I think ideas with lots of kudos get more traction with Esri.
you could use "Find Disconnected Polylines" in the Attribute Rules > Ready to use Rules