Photoshop has a neat feature that lets us make adjustments only to the layer directly underneath, rather than all layers on the stack. It’s called a Clipping Layer. Clip Studio Paint has the same feature, but it doesn’t work by ALT-clicking in between layers. Instead, right-click on the adjustment layer (left thumbnail, NOT the mask), then choose Clip to Layer Below.
To create an adjustment layer, right-click on the part next to the thumbnails (I keep forgetting that) and pick Create Correction Layer.