You want to add the component physical property of Density to the BOM and Parts List for your assemblies.
In order to do that, you need to follow the steps below.
Define the Custom Property in the components of the assembly as in the image below.
The name of the property is not important, but cannot be “Density” or “DENSITY”.
What matters is the value that must be “=<Density>” and you can add the units if you want to display them as well.
You can save this property in your part template file, so that you have it in every new part you create.
Then, in the assembly, add the Custom property column to the BOM.
Even in this case, you can save this setting in your assembly template, so that the column will be available and display by default in the BOM of each assembly you create.
Finally, in the drawing, edit the Parts List style adding the custom column.
Edit the format of the column and rename the column heading.
You can save these settings in the Style Library if you want the column available by default in the Parts List of all the new drawings you create.