Art styles aren’t effects.
There’s no sure recipe to achieving a particular look, only steps for each element in a piece that will produce effects you’ll then combine into a style. I know it sucks to not have an easy set of steps to follow because it makes everything uncertain, but it’s your task as an artist to adapt your workflow to each piece.
I’d say the first step is to take a look at these pieces and identify what you like about them. Is it the lines? The shading? Of which parts and materials? The lighting? You need to break it down into chunks to then discover what they’re meant to represent and ways (plural, there’s often more than one) to produce that one particular effect.
That “what they’re mean to represent” part is important. EG the dragon creature colors. It’s blue to purple, why? The general ambient light is blue, then there’s a light haze in purple from a source outside view in the foreground, hence the parts further back are bluer due the distance to light while the golden mask has many purple highlights for being closer to the purple light source + being a metallic material. It also has a grayish, almost green lighter area on the top. It’s the blue ambient light again, it can read as greenish due yellow surface color + blue light.
Knowing what you’re representing allows you to make decisions that’ll read as style. You can just represent it, omit or play it up. That gray on the mask? It could be omitted, using a light yellow instead, it can be a more or less neutral color like it is, or it could be taken up to eleven by throwing a real green there. Note that there aren’t any other reflections on that mask. The artist chose to omit them to achieve a more sleek look.
This is the art part of the style. There’s the technical, how to achieve the effects themselves. In this case I’m guessing for the first artwork each new step in value is an isolated layer, while the second keeps elements isolated but mostly paints in the same layer. A gradient is applied on them, they build on top of each other behind the lineart layer. Last, on top of it all, a group with very soft gradients with effects like color dodge, multiply for shadows, lighten. Because they’re not contained in areas they create that atmospheric feel.
That’s it, I hope it’s helpful. If possible tell us exactly what you’re trying to do here so we can better answer, is it a tech question (about which effect), an style question or what?