When I want to use the enhance function for a jpeg file in camera raw filter, I have set the file handling to automatic open jpeg in raw in preferences. Opening the jpeg in photoshop and select camera raw filter does not give the enhance option. But in this way I keep changing this preference all the time to get back to normal photoshop and raw. There should be an easier way to do this I think/hope.
The Camera Raw filter is a very limited subset of the full Camera Raw processor (the Photoshop plugin). The filter does not support these functions, you have to do it in the full ACR processor.
If you set the preference to "open jpegs with settings", any jpeg that already has ACR metadata will continue to open through ACR. Without ACR metadata, it goes directly to Photoshop. Ctrl+R from Bridge will force-open it in ACR regardless.
All that said, enhance and super resolution are designed to work on raw data. They will have limited effect on RGB files, and jpeg is particularly unsuited because of the jpeg compression artifacts. Just a heads up, don't expect too much from the result.