Export size

Many screens show more than one physical pixel for each pixel in a design. To stay sharp, images are exported at several scales.

@1x is the base size. @2x has twice the width and height, for high-density screens; @3x has three times, for the densest phone screens.

Export the scales your target devices need, and set the pixel dimensions on purpose, as in the 1200 × 1200 WebP example. Choosing pixel dimensions and choosing file weight are separate decisions.