Does the apple watch se gps rely on an iphone connection in order to record physical activity

Yes, the Apple Watch can record your activity without an iPhone nearby: Use Apple Watch without its paired iPhone - Apple Support. Once the Apple Watch is in range of the iPhone, it will upload your activity to the iPhone. This may take a few minutes.

The GPS only Apple Watch will track your exercise, and when it gets back in range of your iPhone, it will transfer the accumulated data to the Health and Activities apps.