What would happen if space-time began to contract? Assume that the expansion of the universe stops and it starts to contract again. What would happen?

Would only distances between objects get smaller, or are there other effects we can expect?
Given that the expansion of the universe shows us that the distance between galaxies (or rather moreso between galaxy clusters) is increasing, without any change in the distances within or between atoms, or between stars within galaxies (apart from normal stellar motion), and that galaxies themselves are also not expanding, we could assume that a contraction would manifest as a decrease in the distances between galaxies/galaxy clusters.