save image with a new name to reflect the new size
resize it via Document > Resize Document to a size 1.6x the final pixel size
apply the sharpening to the resized image using the Live Unsharp Filter with perhaps 0.3 Radius and 0.5 in Factor
merge the layers by selecting both layers and right-click and choose Merge Visible
now resize to final image size via Document > Resize Document
again apply the sharpening to the resized image using the Live Unsharp Filter with perhaps 0.2-0.3 Radius and 0.5 in Factor
the image may end up brighter than the original so consider adding a Levels adjustment layer to address this + 1.05 brightness
the image may end up less saturated than the original so consider adding a HSL adjustment layer to address this by adding +5 to +9 saturation
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review the sharpening and adjust the opacity for the top most Unsharp Mask filter layer
export to jpeg