XPS 9570 and 2 Dell 49 UltraWides

@Throned  one additional note about the above.  The U4919DW's 5120x1440 resolution in terms of total pixel area is slightly less than a 4K display, and the XPS 15 is definitely capable of running two 4K displays simultaneously.  In fact if you had a Thunderbolt 3 solution to connect two of the 4K displays there, I think you could even add a third 4K display attached via HDMI 2.0.  Again, I haven't tested that myself, but the hardware specs suggest that it will work because the Intel GPU in that system supports up to 3 displays each at 4K 60 Hz.  (Even if you have an NVIDIA GPU, the Intel GPU controls all of the display outputs in this system, as is the case in most dual GPU systems.)

Just make sure you find a cable specifically rated for HDMI 2.0.  It might be billed as a "High Speed / 18 Gbps" cable.

@Throned  the XPS 15 9570 has USB-C and HDMI, not USB-C and DisplayPort.  The HDMI port is rated for HDMI 2.0, and according to the U4919DW's manual, its HDMI input is also capable of HDMI 2.0.  So while I haven't personally tested this setup, the hardware specs suggest that it will work.  Another way to run dual U4919DWs would be through a Thunderbolt 3 to Dual DisplayPort adapter or a full Thunderbolt dock like the WD19TB.  Note that given the bandwidth requirements of the U4919DW (very similar to a 4K 60 Hz display) and the way the WD19TB allocates bandwidth, if you go that route, one of the displays will have to be attached to the "Thunderbolt peripheral" port on the far edge of the dock.  The other display could use any of the other display outputs.

@Throned  sorry for the triple post here, but two more things you should be aware of.  If you plan to attach one of the displays to the system's USB-C/TB3 port using a regular USB-C cable (as opposed to a USB-C to DisplayPort cable or something):

• The USB data traffic you can get through that cable will only be USB 2.0, so any devices you plug into the USB ports built into the display will operate at 2.0 speeds, not 3.x.  This is because a USB-C cable has four high speed lanes, and carrying USB 3.x requires two of them, but carrying enough display bandwidth to run this display at its native resolution from your system requires all 4.  So the display will prioritize video bandwidth.  USB 2.0 is carried through a USB-C connector on pins dedicated to that purpose, so it doesn't detract from the high speed lanes.  If you want USB 3.x, you'll need to connect a separate USB 3.0 cable from the display's "upstream" USB port to the XPS 15.
• You'll still want to keep your XPS 15's power adapter connected directly to the system.  The reason is that the display only provides up to 90W over USB-C, but the XPS 15 is designed for 130W.  It will work from a 90W source, but you may see slower battery charging and/or performance throttling as the system adjusts to the reduced power budget.  Incidentally, the WD19TB can supply up to 130W over its TB3 connection to the system, so that would give you a single cable solution.  (Yes, the official max of the USB PD spec is 100W, but Dell did something proprietary on some of their systems and docks, including the XPS 15 and WD19TB, to push 130W over USB-C/TB3, specifically to support single cable docking on systems like the XPS 15.)

And lastly, out of curiosity what sort of desk do you have that will accommodate dual U4919DWs?  I want to make sure I get one whenever I get new furniture.

@Throned  thanks for the kind words!

I actually have an UPLIFT sit/stand desk that I love.  Not sure if sit/stand is going to be new for you, but if so, you absolutely HAVE to get an anti-fatigue standing mat.  It makes the difference between being able to stand comfortably for about 30 minutes and being able to stand comfortably for hours.  I have a CumulusPRO, which is slightly firmer than their Cumulus9, which is better for long-term standing use cases.  The Cumulus9 is popular in places like kitchens where you might only be washing dishes for a while and where therefore you'll want the extra comfort for the short term even if it won't be as good long-term.

Ok, back to the displays.  The cheapest way is actually your idea of connecting one via USB-C and the other via HDMI 2.0.  The TB3 to Dual DisplayPort adapter was just an alternative suggestion if your original idea doesn't work for some reason, although as I said, it looks like it will.

Any of the options I've mentioned here would allow both displays to be run at their native resolution and refresh rate, so they'll perform identically.  You shouldn't need to use PIP at all.  That's meant for use cases like having different PCs sharing that display or PCs that might not be able to run dual QHD from a single output -- but you shouldn't run into the latter problem.

If you'll just have a mouse and keyboard attached to the display, then just stick with USB 2.0.  Those peripherals (or their wireless receivers) probably don't even support USB 3.0 anyway.  I called that out in case you might be planning to attach an external hard drive to the display or something.  But if you do need USB 3.0, then as I said earlier, you just need to run an additional cable, specifically a regular USB 3.0 cable from the display to one of the USB ports on the XPS 15, and then you're good to go.

As for a dock, if you want to get the WD19TB, you would be able to connect both displays to it and run both at their native resolution and refresh rate.  Then you could optionally run USB 3.0 cables from one or both displays to the dock to light up the USB ports in the display(s), or of course you could just use the USB 3.0 ports built into the dock itself, at which point you might decide you don't even need the USB ports in the display(s) to work.  Or you can use the USB ports in both the display(s) and the dock.  But whatever you do, the single cable from the WD19TB to your XPS will carry enough display bandwidth to run both displays normally, and USB 3.x data, and Ethernet and audio if you use those ports on the dock, and enough power to run the XPS 15 properly.  But of course that solution is quite a bit more expensive than any of these other options, especially your original plan.

Wow I was hoping you responded @jphughan, you seem to be a legend around here.

As for desk, Im looking at either Jasper or a desk from Fully to be able to stand up and sit whenever. What Im realizing these desk are not really that deep for a monitor as big as the ultrawides. They will certainly fit but I want to be able to sit back a little further and not have to turn my head as much.

So based on you solutions I'm assuming the Thunderbolt to dual display is probably the cheapest.

What option you think I should go for as far a best picture quality? I thinking of running split screen or I guess PIP which I understand in the case quality will not matter that much because the screen will be split.

Also whether or not I go adapter or dock, will that put the usb port on the screens back to 3.1 ports? ( I saw in one of your post how they get downgraded due to low bandwidth, haha). Once again not sure if it matter because a mouse and keyboard should run fine over usb 2.0, I would think.

Oh, and I read some of your other post about the power for the 9570 so I'm tracking.

Yaah with the uplift, and see how it sits on the desk before deciding, but I thnk it will be fine. Its funny because all the retractable desk pretty much have the same dimensions just different names haha.

But as for the set up I will definitely be using another computer to hook up to one of the screens for work(work from home). I saw a youtuber bring up a point that it really wont matter much as far as cables or connection when you sharing the display because at that point the monitor become essentially two independent 27'.

But i think I might just rock the USB-c and the hdmi 2.0. I do have to ask though, should I get the USB-c to display port cable you mention, or would a standard USB-c cable do the job?

THe more I think about it Im leaning toward a dock because because of everything such as Ethernet and all that other jazz on it. Let me know if you know of any more cheaper docks that willl support the power requirement for my laptop and still have the bells and whistles as the WD19TB.