libupnp provides pkg-config modules:

  # Linux SDK for UPnP Devices
  libupnp

libupnp provides CMake targets:

  find_package(UPNP CONFIG REQUIRED)
  target_link_libraries(main PRIVATE UPNP::Shared)
  -- or --
  target_link_libraries(main PRIVATE UPNP::Static)

libixml provides CMake targets:

  find_package(IXML CONFIG REQUIRED)
  target_link_libraries(main PRIVATE IXML::Shared)
  -- or --
  target_link_libraries(main PRIVATE IXML::Static)