eSIM in Apple Watch Series 8

Short answer is no. But most carriers that support the Apple Watch only charge $10 U.S. to add an Apple Watch to your existing iPhone service.

Long answer

If you are using an iPhone carrier or plan that does support the Apple Watch, then if your iPhone is always nearby, the Apple Watch will do everything the activated cellular model will do, only using the iPhone’s radios.

Or you can use the Apple Watch Family Plan, but get a degraded experience:

Set up Apple Watch for a family member - Apple Support

Set up a family member’s Apple Watch - Apple Support

Some limitations: Cannot receive SMS/MMS messages, as that depends on a fully paired iPhone. Messaging is pretty much limited to Apple’s Messages, unless the messaging service provides an Apple Watch app. Alarms, alerts, notifications on the iPhone are not sent to the Apple Watch. Apple Pay via a credit card is not available. Also not available: Medications, respiratory rate, irregular heart rhythm notifications, ECG, AFib History, Cycle Tracking, Sleep, Wrist Temperature, Blood Oxygen, Walking Steadiness, Audiobooks, Camera Remote, News, Shortcuts, and the double tap gesture.

Not if you set it up normally.

You can use Family Setup, but that results in the iPhone not being connected to the iPhone, and some features won’t be available. And you need to have a secondary Apple ID for the Watch.

click here ➡️ Set up Apple Watch for a family member - Apple Support