No Red Dot or Ring on the Apple Watch Digital Crown, means you have a GPS only model and went you have a newer iPhone, it will pair with the iPhone and use the iPhone's radios.
The Apple Watch GPS only can do Everything the cellular model can do as long as your iPhone is nearby, where nearby is somewhere in the same 3-4 bedroom home (assuming typical wood frame construction).
https://support.apple.com/en-us/HT205547
If you really want the cellular so that you can leave your iPhone at home when you go for a walk, run, bike ride, etc..., so that you have phone, messaging, weather, etc... then you would need a different Apple Watch. If you want the cellular and are within the retailer's return period (Apple is 14 days), then you could return the Apple Watch and get the cellular model. You could even return it now, and then wait until you have the new iPhone to buy the cellular model.