Garmin Fenix 3, Fenix 3 HR and Fenix 5 GPS watches have excellent functionality for navigation. It is possible to save a current location and navigate to it or navigate a recorded past activity like hiking, running, biking. Manually entering coordinates is also possible.
If you want to explore new and unknown routes you can upload / import a GPX file. To do this, you need to connect the clock to a computer via the USB charger, open the folder of the watch (like a USB flash drive) and copy and paste the .gpx file to NEWFILES folder. If you don’t see the hidden folder, you have to adjust your file explorer options.
After the upload plug out the watch from the charger and wait for it to refresh. If you are not seeing the course after that, maybe there is an issue with the .gpx file. Converting should fix the problem. You can see what I am doing in the video: