OP, please listen to this. IT closet, conduits.
You keep mentioning IoT/5V/12V. Very few items in day-to-day use will be powered like this.
I started with Z-Wave, but ended up moving away from that due to too many devices and single-point-of-failure (the hub). Due to how messages are relayed, one bad or failing device can create a broadcast storm and take down everything. Zigbee competes with the same part of the radio spectrum as WiFi and also has a single-point-of-failure (the hub). I now exclusively use wifi for things. TPlink Kasa for switches and outlets, plug-in switched outlets, Shelly for motion sensors, relays (garage door)
Networking - Router: Use something like pfsense or opnsense. This will control DHCP, DNS, inter-VLAN routing. A separate VLAN and associated firewall rule will allow you to block your “IoT” items from getting out of the network.
Networking - Switching: for ease of use, use UniFi switches. These will control port PoE, VLAN port assignment.
Networking - Wireless: again, for ease of use, use UniFi WAPs. These are easy manage and for a second or third SSID, tagged to a “IoT” VLAN that you block from internet access. Strategically place WAPs for best coverage. At any given time, I have ~75 things on the wireless network amongst 4 WAPs
Home alarm system: 2-wire all door and window reed sensors to the IT closet. Use Konnected or something like that.
Cameras: All good cameras nowadays are PoE. Use a non-consumer grade of ONVIF/RTSP camera, think Axis, or possibly even UniFi Protect. Condiut and ethernet to external (or internal) camera location. Mind your field-of-view angles to insure coverage.
Voice control: Google Home/Alexa/Apple speaker pucks. This is where you will want to find creative places to stick power outlets. Most of these things have their own power brick.
Home audio: For both whole home or TV/theater - Sonos is the 800lb gorilla here. They need mains and ethernet. They can make their own mesh via wifi, but I prefer hard-wiring everything, especially if you can plan it out.
Someone mentioned window shade control. This is where you may need some 12V or proprietary plug; that recessed box would be good for this.
Also, don’t forget a low-voltage conduit from the house’s telecom/data service entrance. You may have copper or coax provider handoff now, but they could give you a fiber handoff one day.
Run one more empty conduit to an area near your mains panel. If you get solar, the combiner panel needs network.
I could go on and on…
Have a look at this video:
https://www.youtube.com/watch?v=IBzanvRn2Hc
Skip the ~7:00-13:30 section as it is not relevant.
In the last segment, he goes over a conduit run from the service entrance. However, I would be running strapped-down rigid conduit since, when pulling cable, there is potential for it to flex (it will absorb the pull force, rather than the force acting on the cable only). His endpoint in the attic area is fine for single-floor homes, but for multiple floors, you will want to run those all the way to the destination.
I would also run conduit for all the wall jacks instead of bare cable.
One thing you can consider: Those new LED puck recessed lighting can double as ceiling access panels. You can end some conduit near those areas. A lot less work to fish wires if you already have 75% of it done
Here is another good reddit discussion “Deciphering what “run conduit everywhere” means for a home remodel”
If you use a single, low-cost wifi router, or your ISP’s CPE device, it may, yes. This is why most people are talking about adding WAPs (wireless access points), which are not routers by the way, they plug into the router (ethernet cable, PoE-powered usually) to “extend” the reach of your wireless and add capacity.