A dimension graphic is not a replacement for technical documentation. Its job is to answer one customer question: “will it fit?”. That is why readability matters more than completeness.
Start with the overall dimensions
Height, width and depth are the basic set for most products. Keep the numbers outside the object rather than placing them on the most visually complex area of the photo.
Show functional dimensions separately
If shelf clearance, hole spacing, connection diameter or seat height matters, show it as a separate dimension. Do not mix it into the overall dimensions if that creates visual clutter.
Units and the source of the data
Every dimension must come from approved documentation, a client measurement or a model with confirmed scale. Do not infer centimetres from a perspective photo without a reference.
It also has to work on a phone
The simplest test is to reduce the graphic to the width of a product card on a smartphone. If the key dimensions disappear, simplify the layout.