This block-based method gives you way more flexibility and you can build the city piece by piece. This Snippet is taken from the second half of the full video: • Octane Render - Build a City Fast or Modul... (this includes scattering using vertex maps, which I have separated for ease, as this is a technique not shared on Youtube yet)
Individual Assets can be purchased here: https://vfxhut.gumroad.com/