Aging really slows down in cooler temperatures, so if the beer needs some aging, that's best done at room temperature or at least cellar temperatures.
But cold conditioning also does things like dropping out polyphenols and so "smooths" out the beer a bit as well.
I'd probably keep the beer at cellar temperatures or higher if it had any "green beer" flavors like cut apples (Acetaldehyde) or a beer with lots of roasty or complex flavors until that was gone and then cold condition it a bit if it needed some more smoothing.
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