@pela I don't understand your remark regarding the absolute size of space. Any length/scale you measure is always relative to some standard. If you have two objects (assuming negligible mass) at rest relatively to each other, the distance between them is what you measure with e.g. a measuring stick. ----

@pela ------This distance is constant if space is locally not expanding. If you have two other objects in a different region of space that is expanding, you will measure the distance between those two objects as increasing. If you then bring your measuring stick back to the objects in the non-expanding region, you will still see them at the initial (smaller) distance. The expansion of the other region is completely irrelevant for what you measure there.