Am electrician and live in a double-wide so I haven’t tinkered with it beyond swapping some devices. Feels good to be able to just do stuff like this, as simple as it is. I was not raised to be very handy so learning all this has been a deliberate process.
Uh, this doesn’t count as a legal, professional consultation and you should always seek a licensed professional when it comes to electricity in your home.
Measure carefully and drill up through the floor or down through the attic to get into/out of the walls
You can get push poles or fishtape from a hardware store to help. I like the Klein braided fiberglass tape, it’s done a great job for me.
There are also drill bits that are long and flexible, you can use those in a pinch if you have to drill through a top/bottom plate but can’t get there easily. Pricey though. Edit to add, the bit shaft usually needs such a long radius of bend that they’re not really practical IMO. Right angle attachments for an impact driver with a spade bit can do a lot tho
However you do it, plan ahead for the future. If that means adding a switch or pull string now to make future projects way easier, it’s worth it