No, Columbia Airport (COA) does not have a lounge, and it never has: this is a small general-aviation field in California's Gold Country foothills, built for local pilots and fly-in visitors rather than scheduled airline passengers. If you searched Columbia airport lounge expecting anything resembling a commercial terminal amenity, the honest answer is that there is no terminal building of that kind here at all.
Columbia sits near the historic town of Columbia, a preserved Gold Rush-era settlement now run as a state historic park, and the airport itself reflects that same small-town, single-runway character: a fuel stop and parking apron for private aircraft, not a passenger gateway. There is no airline service and consequently no lounge network of any kind, branded or otherwise, to speak of.
For a real lounge experience anywhere near this part of the Sierra Nevada foothills, travellers need to look toward Sacramento International Airport, roughly a couple of hours' drive to the west, or San Francisco International Airport further beyond that, both of which run genuine airline and Priority Pass-style lounge networks alongside full commercial terminals. Neither is a quick hop from Columbia, so anyone flying commercially in or out of this region should plan their ground transport accordingly rather than expecting airport amenities near the Gold Country strip itself.
If you are flying into Columbia by private aircraft for Gold Country tourism, wine country visits, or Yosemite-area access, treat the airport as exactly what it is: a small rural strip with fuel and tie-down services, not a place to wait out a layover in comfort. Bring your own refreshments, plan your ground connections in advance, and save any lounge expectations for Sacramento or San Francisco on the commercial side of your trip, since nothing resembling a passenger amenity will be waiting for you at the Gold Country field itself.