My 13 inch M2 Air is, in many ways, the best computer I've ever had. It is light, small, thin, and the battery seems to go on forever. But my computing needs are minimal. I am able to get a browser window and Messages open at the same time, which suits my general usage. When I need other apps--Pages, Numbers, Zoom, FaceTime etc.--I just use Expose to switch.
That said, if I already owned a 16 inch Pro, I do not think I would find value in buying an entirely new laptop just because it was smaller. So, in your situation I would get neither the 13 or 15 inch Air. I would just carry the Pro around and put up with the extra weight--we're only talking a couple of pounds. And it brings with it many advantages: bigger and better screen, much more compute etc.