Dell G5 15 5590 best way to connect two external monitors

@Begy  A few things to clarify right away here:

• If your display supports DisplayPort, I'd recommend a USB-C to DisplayPort cable/adapter instead.  USB-C uses DisplayPort for video output anyway, so USB-C to HDMI adapters/cables have to incorporate an active converter chip to switch that signal to HDMI.  That's just one more thing to pay for and potentially cause problems, so if you don't actually need it, then avoid it.
• Your laptop likely does NOT support being charged over USB-C/TB3, so I would not expect the WD19TB to charge your system.  The WD19TB supports providing up to 130W over USB-C/TB3, but that's only possible when the system also does.  Dell systems like the XPS 15 and some Precision systems support that, but every post I've seen from people using Inspiron Gaming systems indicates that they do NOT support it, even when the system is designed for a 130W power source.  But some Inspiron Gaming systems use 180W power sources, and in that case even if 130W charging was supported, you'd see reduced performance due to using an undersized power source.  So the WD19TB can still be useful if you want to connect high end display setups like dual 4K 60 Hz through a single cable, but I would not expect it to charge your system.
• Absolutely do not get the Dell D6000.  It uses "indirect display" technology called DisplayLink (not to be confused with DisplayPort), and that introduces some drawbacks that can be significant in many use cases, especially gaming.  I wrote about those in the post marked as the answer in this thread.
• In terms of whether you can use the monitors with the NVIDIA RTX GPU, as long as you do NOT use something like the D6000, you will at least be able to use the NVIDIA GPU through NVIDIA Optimus.  That will allow the NVIDIA GPU to handle rendering, so you'll get high performance.  This is how most dual GPU laptops work.  The outputs are actually wired to the Intel GPU, but the NVIDIA GPU can operate as a "render-only" device when needed and pass video through the Intel GPU.  However, in that setup, certain features will NOT be available, such as G-Sync, Adaptive V-Sync, VR, and a few others.  Those require the NVIDIA GPU to have direct control of the display output, which isn't a very common design.  Since this is an Inspiron Gaming system, you might actually find that the HDMI output is wired to the NVIDIA GPU since Dell did that on some systems in order to allow using HDMI-based VR headsets.  But the USB-C/TB3 output might be wired to the Intel GPU.  If you want to check, connect a display to the output you want to test, then go to NVIDIA Control Panel > PhysX Configuration.  In there, you'll find a diagram showing which active displays are wired to which GPU.  Then repeat this test for any other display output you want to test.