Texture Resizing

You can select Texture Resize Type in the Inspector of UnityBakingSettingAsset.

This value is used for lightmap arrays, directional lightmap arrays, and LTC visibility maps. Texture resizing is performed on the asset creation step; simply change the Resize Type and re-run the asset creation; no baking is required.

The left is ResizeType One and the right is ResizeType One Half (asset size is 1/4).