G5 5587 Graphics and External Monitor Support

@Jack63SS  I'll try to answer these questions:

1. Yes it also has Intel Graphics because the Intel GPU is built into the CPU.

2. See the first reply in this thread where I explained how this all works.  The question was about an XPS 15, but the information I provided applies to many other systems.  Assuming you've come back to this post after reading that post, I don't know for sure which outputs are wired to which GPU in your specific system, but if you go to NVIDIA Control Panel and open the PhysX Settings section, it will show you which GPU is controlling each active display.  So if you want to find out about a particular output, connect a display to that output. For what it's worth, on Dell system I've worked with or read about thus far, the USB-C/TB3 output is always wired to the Intel GPU, except the special case of the Precision 7000 Series models that I detailed in that thread.  In terms of when the system uses which GPU on outputs managed by the Intel GPU, typically the NVIDIA drivers reliably detect when an application that would benefit from the NVIDIA GPU's acceleration has been launched and will enable that GPU.  But that can be forced (or prevented) either by creating an application profile in NVIDIA Control Panel or by right-clicking the application shortcut and selecting "Run on graphics processor", which only affects that specific launch of that application.

3 and 4. The Dell product page for your system indicates that it has a USB-C port with Thunderbolt 3 capabilities as well as an HDMI 2.0 output.  Assuming all outputs are wired to the Intel GPU, you can use up to 3 simultaneous independent displays, including the built-in display if you keep it enabled (though you don't have to if you want to run 3 external displays).  In terms of resolutions, an HDMI 2.0 output can support up to 4K 60 Hz (assuming the display supports HDMI 2.0 on its input, and there are some early 4K 60 Hz displays that only accept that over DisplayPort because they were created pre-HDMI 2.0).  A Thunderbolt 3 output when using a Thunderbolt-based peripheral such as a Thunderbolt dock or Thunderbolt 3 to Dual DisplayPort adapter can support up to dual 4K 60 Hz displays or triple 1440p displays just from that output.  If you're using that port as a regular video-capable USB-C port, i.e. without Thunderbolt capabilities, you can run up to a single 4K 60 Hz display, dual 1440p, or triple 1080p displays since you'll have a DisplayPort 1.2 interface driving that port.  But USB-C and Thunderbolt can get a bit tricky.  I wrote a detailed post about the various operating modes of USB-C and Thunderbolt 3, with a particular focus on the impact to possible display configurations, over in this thread if you want all the gory details.

Those two linked threads are quite a bit of reading, but if you have any questions after all of that, feel free to ask!