I just completed service through the dealership on my 2018 Outback 3.6R: Oil Change, Differential Fluid, Brake Fluid, CVT Fluid and when pulling into my driveway a couple days later noticed some fresh fluid stains where I park. I found lots of oily splatter on the transmission oil pan and skid plate and after cleaning, and spending time checking everything I could see I found a loose to the touch drain plug.
It was very awkward to reach without a jack but I was able to tighten it up with a 14mm socket wrench. Due to the angle I wasn't able to get a great picture but the plug is on the drivers side, facing downwards, under the skid plate just forward of the transmission oil pan. I will take it back to the service center tomorrow to make sure its tight and any lost fluid is replaced.
Before I go I would like to be knowledgable on what exactly was leaking but after looking at photos and diagrams online I am unable to confidently pinpoint the exact drain plug.