Powering LED strip lights at two different brightness
Be warned that your understanding of this tech is limited and you'll need to skill up more to pull off a successful project.
The power section
OK, the way I'd do that is by having an always-on 12V (or 24V, better for the voltage drop) power supply in the basement.
I will remain silent on the question of that having a battery back-up, but, if you do have a battery back-up, that favors 12V since TVs, Internet modems and routers are readily available for 12V, not so much for 24V. 12V USB chargers are sold in more places than eggs.
The next step out of the 24V supply will be a timer with PWM dimmer, set to do that &quot;sundown-midnight&quot; thing that you want.
So now we have 2 power sources: Negative always-24V, and &quot;negative sometimes&quot; PWM 24V. LED systems use positive common.
I'd watch voltage drop like a hawk. If I found it advantageous to carry it some distance to remote distribution hubs, I'd use fat aluminum feeder for that, because it's cheap, using MAC Block Connectors for the Al-Cu splices.
The switching section
I would use 3-wire cable (e.g. 12/3*) to carry both of those, with positive common, in 3-wire cable to the switch for each LED segment.   I would use these colors:

Black = always-negative
White with black marking = sometimes-negative PWM
Red = positive common

The switch is a 3-way switch.  The &quot;negative sometimes PWM&quot; goes to one traveler screw, &quot;negative always&quot; goes to the other.  The &quot;3-way common&quot; goes onward to the LED negative.  Positive common passes through to the LED without going to the switch.
The 3-way switch either connects the LED power to &quot;sometime PWM&quot; or &quot;always&quot;.
Now if you actually want &quot;3-way&quot; i.e. multiple switches controlling the light, that is simplicity itself: the first control position (the one power comes into) gets a &quot;4-way&quot; switch instead of the normal 3-way.
Complying with Code
You need to comply with Code's low-voltage wiring rules. The safest way to do that is use wiring methods legal for 120V.  90% of Code is about physical execution of work - correct wiring methods, correct terminations, etc.  You are not allowed to rinky-dink this thing together in a barf of wires all over the place, like a typical workbench electronics project.  You need to comply with NEC 110.12, &quot;neat and workmanlike&quot;.
Power supplies and controllers will need to be physically installed correctly and may need to be UL approved.  You may get in trouble with the AHJ for using non-approved luminaires, NEC 110.2.
The #1 area of concern is complying with the building codes regarding required lighting in any given room.  There must be a light switch in the normal/expected location(s). The light switch must operate a light (a switched 120V receptacle is an acceptable substitute).  You will need to satisfy the AHJ that this is good enough.
There's another reason to use 120V rated cables and wiring methods: Resale value. Later when you are selling this house, you don't want the home inspector going &quot;WTH&quot; and warning the buyer that the lighting circuits are bizarre and unsupportable.  Also, if this experiment fails, absolutely no one will be surprised.  If you make it easy to &quot;fall back&quot; to 120V arrangements and wiring methods, these problems become trivial, and you can proceed with confidence that you always have a plan-B.
The additional cost of wire and proper boxes is trivial compared to the advantage of avoiding difficulties with the mortgage lender and future home buyer.


* Romex for easy fallback to AC mains if stuff doesn't work.  #12 not #14 for voltage drop...
...and because everywhere Code requires a 15A circuit, it accepts a 20A circuit. At the scale I do wiring, the cost diff per foot in #14 vs #12 is not large enough to justify tying up capital in a completely redundant set of wire reels, as well as having to drag those around.