Two customizable legends demonstrate how D3 v5 encodes data through color and size. The color legend uses `scaleOrdinal` to map fruit categories to distinct hues, while the size legend employs `scaleSqrt` to represent numerical values through circle radii. Both legends are constructed through reusable functions that bind data to SVG groups, with legends rendered as circles and text labels. The color legend applies `attr("fill", colorScale)`, while the size legend filters zero values from its ticks and spaces circles vertically.