Hi
Yes it can be done.
Apple still offers a number of features - including a built-in fitness app that can still be used to track runs - when the paired iPhone is not connected or within range.
Features that remain available when the watch and iPhone are disconnected include:
- Track workouts with the built-in Workout app.
- Play music from a synced playlist on Apple Watch.
- Use the watch to tell the time, along with alarms, timers and the stopwatch.
- Keep track of your activity (Stand, Move, Exercise) with the Activity app.
- Display photos from the synced photo album.
- Use Apple Pay to make purchases.
More information:
Use Apple Watch without its paired iPhone
Use the Workout app on your Apple Watch - Apple Support