S2716DGr, enable G-Sync using a USB Type-C to DP cable?

Unknown. Your best bet would to ask the Alienware Laptop owner's here. Maybe one of them as tested such a cable converter from their Alienware Laptop HDMI out port. Be sure to mention to them your Laptop model specifications, operating system, and S2716DG monitor in your post.

Ok thanks @DELL-Chris M , is there any converter cable you can recommend then for a laptop with no DP outport? I would like to make use of my 1060 GPU to get at least higher than 60 Hz on this screen.

The S2716DG HDMI 1.4 in port is locked at 60Hz (see S2716DG User's Guide page 12). 

The S2716DG DP in port can do G-Sync 85Hz/100Hz/120Hz/144Hz. You can see on page 23 that we only tested G-Sync via a source PC DP 1.2 or greater DP out port.

So if you follow the instructions in below picture, "How to Use and Troubleshoot the Dell S2716DG", and do not see G-Sync, then the laptop --> USB Type-C to DP--> S2716DG DP in port is not being "seen" by the S2716DG as G-Sync capable.

Sorry @jepp96 did you at all come right with a cable that will work for your needs? I am looking for the same thing. 

@Cwmacker  G-Sync requires a display that supports it and also requires that the signal be native DisplayPort (except for a G-Sync variant only available on GeForce 16 Series cards and above with certain LG OLED TVs, which uses HDMI, but that appears to be a rebrand of HDMI VRR).  A USB-C port uses DisplayPort for video output natively, and a USB-C to DP cable keeps that signal as DisplayPort, as opposed to a USB-C to HDMI adapter/cable that would use a converter chip within the adapter/cable to switch that over to HDMI.  So that part is all good.

But the additional key requirement, and the one where I think @jepp96  had trouble based on the description of not even seeing the section of NVIDIA Control Panel to enable G-Sync, is that the display output you're using needs to be directly controlled by an NVIDIA GPU.  Many laptops with both Intel and NVIDIA GPUs wire most or even all outputs to the Intel GPU so that the NVIDIA GPU can be completely disabled when its performance isn't required, which saves battery life.  In these designs, the NVIDIA GPU when needed only works via NVIDIA Optimus, which is a technology that allows it to do all of the rendering work and then pass completed video frames through the Intel GPU for final output to displays.  But there are certain technologies that can't pass through Intel GPUs, such as (as of this writing) G-Sync, Adaptive V-Sync, VR, stereoscopic 3D, and possibly others. A very small handful of systems allow users to change which GPU controls various display outputs, but that’s only possible if the motherboard was designed to allow that sort of flexibility. If your system doesn’t have that option and doesn’t have any DisplayPort-based outputs wired directly to the NVIDIA GPU, then you can’t use G-Sync.