Unpairing and repairing to new iPhone

Hi, I’m just after my first Apple Watch series 7, and been watch a few tutorials on YouTube, I buy a new iPhone every year to the latest model. Do I need to restore my Apple Watch every time when changing to a new iPhone ?

I thought when changing to a new iPhone all I had to do was create an iPhone backup to iCloud restore my iPhone to factory settings, on new iPhone restore from backup and Apple Watch would pair to new iPhone automatically without unpairing and repairing to new iPhone

thanks in advance