Something that's Dickensian brings the writing of Charles Dickens to mind, especially his vivid scenes of poverty in Victorian England.
While you can describe a story that's written in the style of "Oliver Twist" or "Great Expectations" as Dickensian, it's more common to use the adjective when you talk about poverty or extreme social inequality, subjects that Dickens famously examined in his novels. Modern journalists often describe bleak scenes of hardship — homeless families, hungry children, squalid living spaces, or unsafe working conditions — as Dickensian.