Right-click in the Gallery window and select Import . Apply: Drag the PowerGrade onto your clip's node graph.
When you download the legitimate version, you usually receive: The PowerGrade file. A User Guide (PDF) explaining the node tree.
It sounds like you’re looking for the PowerGrade by Tom Bolles, which is a popular DaVinci Resolve tool designed to mimic the look of 16mm film [1, 2]. Where to find it