Is there a way I can make the guy on the left match the art style for the rest of the image?

[glad wharf]

The guy in the left was pulled from another image. He is clearly made with finer detail than the background image. Can I do something quick and simple to make it look as though he has been painted with thicker brushstrokes like the men on the right?

Also does he totally look like he doesn't belong in the picture or have I done a decent job of incorporating him?

[slim violet]

I think colour-wise, it's rather good, it's the looser brush work on the background that gives it away, as you detected.
I would try the oil paint parametric filter see screenshot
To find it, as far as I know, you need to "call" it through the magnifying glass icon you will find at the top right of the interface, and type "parametric" in the search box. (it's a bug, it should be in "filters")
Obviously run it only on the layer for that guy, and play with the sliders.

You can run it as a smart object to retain even more control

[glad wharf]

Thank you I'll give it a try. Could you comment on something else please? Is he the correct size for the perspective? Should he be smaller or larger or is the scale fine?

[wind beacon]

Gave +1 Creative Carma to @slim violet (current: #6 - 1124)

[slim violet]

Since we don't really have the blurriness that could indicate the real distance, and assuming he's on the same plane as the area between the second guy and the third one, I think it's correct
But it's this guy that bothers me. It looks like a GenAI botched it a bit. Don't know if it's intentional

[glad wharf]

I dont think the original image was gen AIed. It is a lesser artwork for a triple AAA strategy game. All of the digital artists for that game are on artstation so you can pretty much get any artwork you see in game.

[slim violet]

I'm not saying that was the case, I'm saying that's the impression it gives