does iwatch come with a usb-c adapter

Th\e Apple Watch 8 comes with a magnetic charger with a USB-C connector. It does not come with a power adapter. If you don't have a USB-C power adapter from another device that you can use, one option is Buy 20W USB-C Power Adapter - Apple

You can buy any USB-C power adapter from Apple or a 3rd party.

You an by a USB-C to USB-A adapter (less than $10 U.S.)

If you have a personal computer with a USB-C port, you can plug the charging puck into the personal computer.

If you mean the power adapter, no. Apple hasn't include one for quite some time. You must buy one separately from a third-party or here:

Buy 20W USB-C Power Adapter - Apple