You don't have to yell

You can access everything through the Google Home app on the device and turn on or off whatever you like, and even make automations that control several items at once. For example at Christmas I set up several automations like the following with our smart plugs:
- Turn on daytime Christmas lights - turned on the tree and inside lights, but nothing in the windows.
- Turn on all Christmas lights - turned on the tree, inside lights, lights in the window, etc.
You get the idea...
You could of course say "Hey Google... turn on daytime Christmas lights", but you can also just click on that automation in the Home app and it does the same thing, Very non-techie friendly once set up.
Apple Home has similar set up options. I haven't experimented with that yet, but Google Home works on iPhone as well, you just need to jump through more hoops if you want to talk to it. You need Google Assistant installed and then set it up so you can trigger from Siri for voice. But that's a separate topic...
If you buy devices, make sure you check what system they are compatible with. Some work with Google Home, Apple Home, or both as I understand.