Can’t pair the 2

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How to pair your Apple Watch with a new iPhone – Apple Support

I've just bought my first Apple Watch 6. I have an iPhone 11 Pro Max. I can not see my Apple Watch on my iPhones bluetooth paired list. But it still sends me iMessages etc. I know there is an update for the watch (7.2), but it only opens up the T&C on my iPhone but will. not install. Any ideas? Thanks