What happens to the average density of the cosmos as the volume of space increases due to expansion?

It steadily drops, weakening large-scale gravitational influence

The accelerating expansion of the universe directly impacts the average density of matter spread throughout space. As the total volume of space increases due to this expansion, the same amount of matter becomes distributed over a larger area, causing the average density to drop continually. Because gravity relies on density to maintain a strong influence over large regions, this decreasing density weakens the large-scale gravitational forces that might otherwise cause the universe to collapse or continue forming massive structures indefinitely. The structures that formed early, when density was high, survive, but the empty space around them expands aggressively.