Extending lines using ArcGIS Pro

ArcGIS Pro has two ways to extend polylines that you have not mentioned in your question:

1. You can Extend or trim a polyline feature when editing:

In the Modify Features pane, the Extend or Trim tool extends a selected line feature to an existing feature boundary or trims it where they intersect. The tool pane contains one multitool that extends or trims a line, and two preset tools that exclusively extend and trim.

2. If you have a Standard or Advanced level license, then you can use the Extend Line (Editing) tool:

This tool extends line segments to the first intersecting feature within a specified distance. If no intersecting feature is within the specified distance, the line segment will not be extended. Tool use is intended for quality control tasks such as cleaning up topology errors in features that were digitized without having set proper snapping environments.