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

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

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.