You can use layer blending modes to lighten or darken an image. A common trick is to duplicate a layer and then change it to Overlay mode to darken it, or Screen to lighten it. Here’s the thing: Duplicating the layer doubles
the file size. You can get the same result by creating a dummy adjustment layer. Create any adjustment layer,
Levels, Curves, Hue/Saturation, etc. by going to the Layer>New Adjustment Layer menu. If you don’t make any changes in the Properties panel, the image won’t change. Instead, just change its blending mode in the Layers panel and Photoshop will think it’s a duplicate layer. 

This tip originally published in Colin Smith’s “Photoshop Tips” column in the September, 2020 issue of Photoshop User magazine.