How does the density of a large piece of aluminum compare to a small piece

A small piece of aluminum the size of a penny will have the exact same density as a piece the size of a football. the reason for this is because density is not dependent on the size of a sample.

the mass density or density of a material is defined as its mass per unit volume. the mass density of a material varies with temperature and pressure. (The variance is typically small for solids and liquids and much greater for gasses.) Increasing the pressure on an object decreases the volume of the object and therefore increase its density. Increasing the temperature of a substance (with some exceptions) decreases its density by increasing the volume of that substance. so unless the temperature or pressure is different the two pieces of aluminum will always have the same density.

It's the same because density isn't affected by the size of the sample