Kant argued (at least as I understand him) that it is impossible to conceive of the/a world absent space and time, due to the constitution of our cognitive faculties. I think he was clearly wrong, since I think I can conceive of at least one logically possible world with neither space nor time, to say nothing of worlds with one but not the other. Consider a world of immaterial monads which are not extended in space (by reason of being immaterial), and imagine that they are at ‘rest’ (they are in a metaphysically quiescent state) such that they have properties and/or relations which do not bring about any successive causes. If those monads do not have petites perceptions then, on the Leibnizian view of space, space does not exist in the logically possible world including only those monads.
However, Kant’s claim can be modified to ‘it is impossible to imagine a world absent space and time‘. There may be many things I can conceive of and which I cannot imagine. I cannot imagine God (I don’t even understand when people say they think they can – I think they are just confused), but I understand what the phrase “God exists” means. More mundanely, William Lane Craig offered the example on his podcast recently that one can imagine and conceive of a four sided figure, but cannot imagine a thousand sided figure even though one could conceive of it. There are plenty of things we can conceive of and not imagine.
I could be wrong about Kant though.