Hello where would you think the best place to add Length x Width x Height to the products? I would think that this would then update the shipping details with costs. Rules don't seem to facilitate this. Recommendation for dynamic Store product data updates
To enable this, when you add the Store Product Details field to your channel field group you will see an option to Enable Dynamic Weight & Dimensions:
You need to set this to Yes so they can be submitted from the front-end.
As long as you setup your shipping rules then they will match the selected dimensions of the product and increase or decrease shipping cost accordingly.