I’d u am in a remote location outside my cell provider range will the spa call work

You must be in range of a cellular network for SOS to work. It doesn't necessarily have to be your network provider.

There are places in the USA where there intentionally is no cellular service, so people don't become dependent on it and instead prepare to make proper provisions for being on their own. Some national parks, for example.

You will need to use a landline phone.

If you have Wi-Fi calling enabled on your account that should work with your phone, but not with your watch. With Wi-Fi you could also create a Google Voice number and use it, or other 3rd party comm apps such as Skype.