How to save to exact texture size?

Due to always a bit of blurry pixel to pixel textures I have to work in double of my target resolution in Painter  and then  crop and downscale it with affinity photo thanks to its slice based  auto export and Lanczos3  resample.  But it gets really tiresom quickly.

Is there a way to downscale  at export in Painter itself ?   I weirdly  see only max axis  dimention . Can it be specified  by an exact size ?   I hardly ever work on square shaped textures.