Apple watch SE

Hello and thank you for using Apple Discussions.

It depends on if your Apple Watch SE is GPS or GPS + Cellular.

Let me explain further:

If it is GPS only, your iPhone has to be within the Bluetooth range.

If you have a GPS + Cellular (Which is set up) you can have your Apple Watch with you and not the iPhone.

If you have a GPS + Cellular Apple Watch SE and Cellular is not set up, you can check this link to help you set up your Apple Watch Cellular. Set up cellular on Apple Watch - Apple Support

If you have any further questions, do not hesitate to ask.

Thanks.

30 feet is optimistic if it is a metal locker which will tend to act as a Faraday cage and block radio signals.

Out in the open, I've been able to be 50-60 feet (15-18 meters) away from my iPhone, with maybe a room wall or floor in-between.

The watch and phone have to be in bluetooth range(about 30 feet).

If you have a cellular watch then that doesn't apply.