You’d need a dock. HDMI alternate mode is probably what the USB-C port is being used for with that adapter (just a guess!) and I don’t think you can get two independent display outputs out of that.
Succeeding the 3007WFP, Dell’s latest 30-inch deskbuster LCD, the 3008WFP, packs the much-ballyhooed DisplayPort input with its visual-cortex-pleasing 2560×1600 resolution support and 10.8Gbps data ...
The Digital Video Interface and Serial Digital Interface standards are similar in concept but very different in execution. Backward compatible with the High Definition Multimedia Interface, or HDMI, ...