We drove to Lake Wenatchee during a winter day and the road was cleared to the state park - in case you want to visit the area. No problem over the pass that day and night. We had a minivan and no chains. I would assume you would need chains to visit Plain even via 207, but from Leavenworth, sketchy over that ridge.

Everyone there seemed to have a plow of some sort.

Sasquatch and sled dogs

Usually any car will do, as long as the road gets plowed, although some vehicles handle better than others in deep snow. You may have to dig your vehicle and driveway out with a shovel, but generally the county and state roads get plowed reliably and you can just drive a normal car on them. People use snow shovels, snowblowers, tractors, or hire private plow trucks to clear their driveways. Chains are nice to have for driving during storms or on ice or on snow covered pavement, but might not be necessary depending on the vehicle and tires.

Source: I live in rural Okanogan county, I think there’s been around 55” of snow at my house so far this season.