[NAME]  Dual 4K 60 Hz through a dock is best achieved with a dock and system that support Thunderbolt. That was an option on the 5510, so does your build include Thunderbolt or just regular USB-C? If it’s Thunderbolt, then the Dell WD19TBS is what you want, and you’d have to cable it as specified in its user guide in the appropriate way for an HBR2 system, which means that for dual 4K 60 Hz, one display will need to be concerned to the downstream TB3 port at the edge of the dock. A USB-C to DP cable is fine for that purpose. The other display can use any other output. If you don’t have Thunderbolt, then your system could only run a single 4K display and only at 30 Hz through a USB-C dock. The only option for dual 4K 60 Hz in that case would be a dock that used “indirect display” technology like DisplayLink — not to be confused with DisplayPort. The Dell D6000 dock is one such dock, but DisplayLink comes with some drawbacks that can be significant in some use cases, which I wrote about in the post marked as the answer in this thread. Also note that the D6000 only provides 65W of power, which I’m not sure is enough for all configurations of the Latitude 5510. Check the output on the power adapter that came with your system. If you don’t have Thunderbolt and DisplayLink and/or power issues are unacceptable to you, then unfortunately you have the wrong system for your goals. A USB-C to DP cable connected directly to your system would allow one 4K 60 Hz display, but then you can’t have a traditional dock at all since you only have a single USB-C port on that system. And the HDMI port on that system only supports HDMI 1.4, which doesn’t allow 4K 60 Hz (only 4K 30 Hz or 1440p 60 Hz), so you wouldn’t have a way to run that second display.
I am wanting a suitable docking station for a Latitude 5510 to drive 2 x S3221QS UHD 3840 x 2160 monitors. My preference is for a Dell docking station to avoid any compatibility issues, however if a better option is available I would consider it. If this is not possible, is it possible to use something like a USB -> HDMI/DisplayPort connected video adapter module. Any help is appreciated.
Docking station for a Latitude 5510 to drive 2 x S3221QS UHD 3840 x 2160 
monitors.