Universal expansion occurs on the grandest of scales. ie, even structures as enormous as galaxies, with hundreds of billions of stars contained in them, basically aren’t affected by cosmic expansion. Gravity wins out at even that scale and holds them together. UE takes place in the incomprehensibly large regions between galaxies.
The rubber sheet analogy for gravity is flawed.
It assumes you rubber sheet has nothing under it.
Imagine the rubber sheet placed over a small kiddie pool filled with water and the sheet sealed to the top edge of the pool. Now put the bowling ball on it.
The ball still goes down, but at the furthest points from the ball the sheet rises UP.... because the fabric of space time is uncompressable in the 4th spatial dimension.
there is your anti gravitational force driving galaxies apart....