With the built-in maps functionality of the Garmin Fenix 6 Pro and many other Garmin devices, you have the ability to plot routes and export them to your device. For watches, this is perfect for hiking, but I have used it when doing walks around a new city for sightseeing. Of course, on a bike, it is even better giving you routing information without relying on your phone.
For cycling, I mainly use the Garmin app to plot a route then export it. If you can find a pre-made GPX route for a hike or bike ride you can also import it into Garmin Connect then transfer it to your device.
Google Maps does not have a native GPX export functionality, and when I am plotting walks for breaks in a city this is my prefered medium.
It turns out, it is quite simple to get the GPX version of a plotted Google map.