There's no need for a Thunderbolt-to-DVI adapter. As Mr. Rayfield pointed out, a USB-C to DVI adapter or cable will do. It's easier and cheaper to adapt USB-C (DisplayPort) to DVI than to adapt USB-C (Thunderbolt) to DVI – and you wouldn't see any practical advantage to doing it the more expensive way. So all of the adapters run off the DisplayPort signal, and ignore the fact that most Macs with USB-C ports can also deliver Thunderbolt signals on demand.
The Cinema Display (23-inch DVI) has a resolution of 1920x1200 pixels, which should be within the capability of the more common single-link adapters and adapter cables.
If you search Amazon for "USB-C to DVI cable", a lot of adapters (meant to be used with a separate DVI cable) and one-piece cables (USB-C on one end, DVI on the other) come up.