Deep[ Creek Lake is one of the best big bluegill lakes in the nation. There are 2 strategies for taking big bluegills at DCL. The first is to fish in the arm coves at 25 feet or so. You should look for 'sticky' hard bottoms and fish tiny tungsten jigs with maggots, waxies or micro plastics. You should fish the bottom six inches & avoid sudden jig movements. Some good arms are Turkey Neck between the Yacht Club and the cables, and Mchenry mid cove.
The other option is to fish weed beds, generally the weedier the better. These fish can be caught at various depths, so fish the water column. There are numerous weed beds located throughout DCL.
Hope this helps. Tight lines!