Here is a wall sleeve I made for dry wall. This is two-part 1.75inch diameter tube that can fit three-prong plugs that are bent at a 90deg angle (L shaped). Max length is 142.5mm adjusting for the part that fits on the wall. The smaller tube should fit into the larger tube when fitted together from each side of the wall.

Print it. Cut the hole in the drywall. Glue using clear silicone. Feed the cord through. Done.

Attribution - Creative Commons

drywallplugsleeve