To answer your question, I couldn't successfully connect my external display via hdmi using single USB C or two USB C. BTW I'm using a Thunderbolt 3 -> DP cable for both monitors and have upgraded the WD19TB firmware to its latest version. One thing i noticed ist that it does not matter whether you use a single or both usb connectors, it will also work with only one cable connected in case it works at all.

Adaptable to your workload: conveniently choose between a single USB-C cable or dual USB-C functionality, a feature Compatible with our precision 7000 workstations.HBR2 is DP 1.2 (5.4 Gbps maximum link rate per lane). With DP overhead, the effective data rate is 4.3 Gbps per lane. Laptop supports HBR2 if the DisplayPort supports DP 1.2 protocol.

Open the Windows Display Properties and go to Multiple Displays control to set the display to the extended mode. MacRumors attracts a broad audience of both consumers and professionals interested in the latest technologies and products. We also boast an active community focused on purchasing decisions and technical aspects of the iPhone, iPod, iPad, and Mac platforms. External monitors require a certain amount of bandwidth to work properly. Monitors with higher resolution require more bandwidth.Reset the monitor to Factory Defaults. See the User Guide of your monitor for more information about how to reset the monitor to factory defaults.

I also flashed the new firmware using a windows pc, since macos is not supported officially but i did not notice any changes.IDC Whitepaper: “Optimizing Performance with Frequent Server Replacements for Enterprises” commissioned by Dell Technologies and Intel, March 2021. Results are based on interviews with 18 IT practitioners and decision makers at midsize and large enterprises and a web survey of 707 IT practitioners and decision makers at midsize and larger enterprises using Dell Technologies server solutions across 7 industries. See full whitepaper: https://www.delltechnologies.com/resources/en-us/asset/white-papers/products/servers/server-infrastructure-resiliency-enterprise-whitepaper.pdf

Power your day: Dell ExpressCharge allows you to charge up to 80% in one hour , making it the most efficient way to manage the workday. Ultimate connectivity: Dual USB-C connectivity makes it easier than ever to deliver power, data, audio and video as well as connect to system peripherals, no matter what system you use. Plus, with support for up to four displays, including a single 5K and dual 4K monitors , you can connect to everything you need. Note: To learn more about updating the BIOS on a Dell computer, see the Dell knowledge base article: Dell BIOS UpdatesI just wanted to echo this reply and state that this is my exact experience except I do not have the DisplayLink drivers installed. Nice thing is laptop can remain stored with cover shut while this system is working. Tremendous improvement to productivity. Estimated valueis Dell’s estimate of product value based on industry data, including the prices at which third-party retailers have offered or valued the same or comparable products, in its most recent survey of major online and/or off-line retailers. Third-party retailer data may not be based on actual sales. Note: To learn more about what type of USB-C port is available on your laptop, see the User Guide of the laptop.