All of Apple’s operating systems are designed for high PPI displays. There’s no font hinting, no subpixel AA. Apple decided long ago that a high pixel density is a baseline requirement for any device they sell, including computers, since the 2010s. You can use a low PPI external but it will not look good.

Given that the smartphone industry also adopted high PPI displays as a minimum standard, it’s actually the external display industry that is the odd one out here. Low PPI displays should have gone the way of CRTs, but they cling on.