Block diagram makerfrom plain language, free.

block
  columns 4
  phone(("Phone app")):2 voice(("Voice assistant")):2
  space:4
  block:cloud:4
    columns 3
    accounts["Accounts and sign-in"] rules["Automation rules"] alerts["Push alerts"]
  end
  space:4
  space hub["Home hub"]:2 space
  space:4
  motion["Motion sensor"] door["Door sensor"] thermostat["Thermostat"] lights["Smart lights"]
  phone --> accounts
  voice --> rules
  accounts --> hub
  rules --> hub
  hub --> alerts
  motion --> hub
  door --> hub
  thermostat --> hub
  lights --> hub
  classDef cloudService fill:#e0f2fe,stroke:#0284c7;
  classDef device fill:#f0fdf4,stroke:#16a34a;
  classDef center fill:#fef9c3,stroke:#ca8a04;
  class accounts,rules,alerts cloudService
  class motion,door,thermostat,lights device
  class hub center