To set the resolution of individual images when packing in Spine, you can manually resize the images in an external program like Photoshop before packing them. Spine's texture packer does not currently support setting individual image resolutions directly during the packing process. However, you can control the overall scale of the packed images by adjusting the scale settings in the texture packer. For more precise control, resizing images externally remains the best approach.

Additionally, you might want to explore the Scale tag here:
https://esotericsoftware.com/spine-import-psd/#Group-and-layer-tags

[scale:number] Layers are scaled. Their attachments are scaled inversely so that they appear the same size in Spine.