I have a XPS 13. Yes it supports Thunderbolt 3 over the USB-C connection. You can get a number of double display adapters (4K @ 60Hz x 2) but that's all they support. No power, USB, Ethernet etc. There are a number of adapters that do USB-C only and thus only have HDMI or VGA outputs. The main issue for me is the lack of 60Hz output. I've lived with 30Hz though and for desktop/programming it's really not that bad.

The Dell TB15 dock linked on Amazon was released early this year but had massive driver, stability etc problems. Even with driver, BIOS etc updates it was still dodgy. That's where all those bad Amazon reviews came from.

I noticed I got a Thunderbolt firmware update just recently for my XPS 13 so maybe that's fixed it finally? They had stopped selling the TB15 completely for a while. Perhaps it's "fixed" and back on the market? On paper it will do what Matt is looking for (and me too).

I was looking for a single plug in solution. Ethernet, 4k@60Hz DisplayPort output, some USB ports and USB-C power pass through. That way I could dock my laptop with one cable.

It has one really dumb design feature. The cable comes out on the left but the XPS 13 also has the USB-C port on the left. The cable is short too so it's quite awkward to place on the desk.