Apple Watch not pairing with new phone

I’ve just upgraded my iPhone SE to the IPhone 15 and unpaired my Apple Watch.

But I’ve not been able to repair my Watch to the new phone. My phone is saying there isn’t a Watch nearby to pair to and my Watch itself is still showing that it’s paired to my old phone but the symbol is up to show that my Watch is not near the phone.

How can I pair my Watch to my new phone?