You can import the ride into the edge as a course and view the course beforehand. But the course won't display on the map while you're riding without trying to route you.
link - Uploading a Third-Party Course into Garmin Connect
link - Steps to Send a Course to a Device Using the Garmin Connect App
link - Sending a Saved Course from Garmin Connect Web to a Compatible Garmin Device
After the course is imported into the edge, to view the map, locate the edge's menu > navigation > courses > select a course > select > map. Again this will not display in the edge's map during your ride without routing you.
Thank you for choosing Garmin,
Bea
Product Support
Garmin International
For 24-hour access to support videos, manuals, FAQs & more, visit the Support Center.