How to enable dual display (laptop display + external monitor) on fedora28 with Lenova machine

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On my older Fedora systems (using a Dell laptop) plugging the external monitor to the HDMI input was sufficient; Both monitors appeared in settings/display and I could adjust resolution etc. On my new laptop I see a single unknown monitor (the laptop display) whether or not the external monitor is plugged in. The Fn F7 key does nothing, and xrandr only shows the single monitor:

*xrandr --listmonitors
xrandr: Failed to get size of gamma for output default
Monitors: 1
 0: +*default 1920/508x1080/286+0+0  default*

The BIOS offers the ability to set either the laptop display or external display as the boot option ie where the username and password appear. With the BIOS set to external and the external monitor connected to the HDMI port, I do indeed see my display on the external monitor. The laptop display is dark, and xrandr and the Settings/display page shows a single monitor as before. Is there a better driver available for Intel UHD Graphics 620 card, or a way to manually set the X11 config file?

Machine components:
System:
  Host: lenolin-triumf-ca Kernel: 4.17.17-200.fc28.x86_64 x86_64 bits: 64 
  compiler: gcc v: 8.1.1 Desktop: Gnome 3.28.3 
  Distro: Fedora release 28 (Twenty Eight) 
Machine:
  Type: Laptop System: LENOVO product: 20L50011US v: ThinkPad T480 
  serial: <filter> 
  Mobo: LENOVO model: 20L50011US v: SDK0J40697 WIN serial: <filter> 
  UEFI: LENOVO v: N24ET41W (1.16 ) date: 07/18/2018 
Battery:
  ID-1: BAT0 charge: 22.7 Wh condition: 23.9/23.9 Wh (100%) 
  model: LGC 01AV489 status: Unknown 
  ID-2: BAT1 charge: 21.3 Wh condition: 23.9/23.9 Wh (100%) 
  model: LGC 01AV490 status: Discharging 
Memory:
  Array-1: capacity: 32 GiB slots: 2 EC: None max module size: 16 GiB 
  note: est. 
  Device-1: ChannelA-DIMM0 size: 8 GiB speed: 2400 MT/s type: DDR4 
  Device-2: ChannelB-DIMM0 size: No Module Installed 
CPU:
  Topology: Quad Core model: Intel Core i5-8350U bits: 64 type: MT MCP 
  arch: Kaby Lake rev: A L2 cache: 6144 KiB 
  flags: lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 30336 
  Speed: 753 MHz min/max: 400/3600 MHz Core speeds (MHz): 1: 740 2: 733 
  3: 744 4: 743 5: 744 6: 782 7: 775 8: 763 
Graphics:
  Card-1: Intel UHD Graphics 620 driver: N/A bus ID: 00:02.0 
  Display: x11 server: Fedora Project X.org 1.19.6 driver: fbdev 
  unloaded: modesetting,vesa resolution: 1920x1080~77Hz 
  OpenGL: renderer: llvmpipe (LLVM 6.0 256 bits) v: 3.3 Mesa 18.0.5 
  direct render: Yes 
Audio:
  Card-1: Intel Sunrise Point-LP HD Audio driver: snd_hda_intel v: kernel 
  bus ID: 00:1f.3 
  Sound Server: ALSA v: k4.17.17-200.fc28.x86_64 
Network:
  Card-1: Intel Ethernet I219-LM driver: e1000e v: 3.2.6-k port: N/A 
  bus ID: 00:1f.6 
  IF: enp0s31f6 state: up speed: 1000 Mbps duplex: full mac: <filter> 
  Card-2: Intel Wireless 8265 / 8275 driver: iwlwifi v: kernel bus ID: 03:00 
  IF: wlp3s0 state: up mac: <filter> 
  Card-3: IMC Networks Integrated ...