Creating a number for my Apple Watch

No.

You either pair to your iPhone and use your iPhone's number with a carrier that supports the Apple Watch.

Or you degrade the Apple Watch feature set, and pretend your are your own dependent child or aging relative, and then you can get a Apple Watch Family Plan from a supporting carrier for your Apple Watch.

There is a 3rd option, but you most likely do not want that. Your iPhone most likely supports a 2nd eSIM. You could get a plan from a carrier that support the Apple Watch for the eSIM and then pair your Apple Watch to the iPhone specifying the eSIM account. But that is only really a useful feature if your normal cellular plan is paid for by your company and the plan does not include an Apple Watch.

There are 2 Apple Watch cellular modes, and the GPS only mode

You pair to your iPhone, and share your iPhone's number, assuming you are using a cellular provider that supports the Apple Watch, and the fee is generally $10 U.S. per month. The Apple Watch has the same phone number as the iPhone.

You use the Apple Watch Family Plan, and treat the Apple Watch as if it is being used by a dependent child or an aging relative. In this mode the Apple gets a phone number from a cellular provider that supports the Apple Watch Family Plan (more expensive than the $10 U.S. for sharing the iPhone's phone number). In this mode, the Apple Watch is degraded. It lacks features that normally depend on being paired to the iPhone, but because it is being treaded as belonging to a different person, the parent's controlling iPhone does not share with the Apple Watch.

An Apple Watch in GPS only mode can do everything a cellular Apple Watch can do AS LONG AS the iPhone is nearby. When away from the iPhone the GPS only mode Apple Watch can still track your exercise, and play music and Podcasts stored on the Apple Watch. When away from the iPhone it lacks the ability to make and receive phone calls, texts, get weather, or any other Internet related task.