I couldn't found Shadow and highlight adjustment layer in Photoshop CC 2018 ver 19.0
Got to Image > Adjustments > Shadow/Highlights. It also works with Smart Object layer, by the way.
If you still do not see Shadows/Highlights then check that eyeball on the right side is visible from Edit > Menus > Image > Adjustments > Shadows/Highlights.
Shadows & Highlights has never been an adjustment layer. It is only available in the adjustments menu as shown by Bojan
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