The documentation is wrong. I have an Inspiron 5510 with i5-11320H (no dGPU) and I confirm that 4K60Hz is possible through both the USB-C port and the HDMI port.
Thinking about getting the 5510 with Iris Xe graphics if it can support 4k60 UHD graphics and ATMOS through HDMI 2.0.   I know it's HDMI 2.0 if you get it with the Nvidia graphics.  But I'm asking about the Intel Iris Xe graphics.  
Is Inspiron 5510 with Intel Iris Xe graphics going to be HDMI 2.0 compatible?