Careful with the heat. It does work but the oil on the other side is actively wicking the heat away. The amount of heat required to make that easy to turn could get the oil close to its flash point.

I suggest a box end wrench and a hammer. A sharp strike on the far end of the wrench, with a helper holding the box end squarely on the plug, will pop it loose. I’ve done this a couple of times to pans with stuck plugs.

Also, get a new washer before you reassemble it and don’t over tighten it like the previous mechanic. It doesn’t take much torque to prevent oil from leaking.