Moose head

Love the moose head idea, but realistically choose rugs, art, throws, pillows in warm Western/Native American palettes--golds, rusty reds,turquoise. Choose unfinished, rustic finishes--iron, wood trims. Upholstered pieces covered in the same colors, leather,or textured fabrics.

Black and white can also veer Western, combined with leather and rustic pieces.

Your wall paint is fine as are countertops, wood floor, etc. So you have a good starting place.

Here's a Pinterest link on how to create cowboy man cave. Since you lean more Western, hold back to to cowboy stuff.

https://www.pinterest.com/pin/626774473123611467/

I'd start by paint the walls and ceiling a dark color. What colors do you like?

What colors Don't you like? Will there be a TV mounted on the wall? any games? Football fan? Basketball? etc.

Why do you ask? This looks very much like an AI-generated image to me.

This is a 3D visual of layout but not my selections. Wanted to give a better visual of the space. How would you change it to make it moody?

https://www.architecturaldigest.com/gallery/ralph-lauren-colorado-ranch-slideshow

I'd start at the far end of the kitchen with your design because that is where you can make the biggest impact.

Do a faux treatment on the wall...brick, or boards. Hang some black and white photos which add to the feel. Love this one:

There are so many ways that your post could be interpreted. There are many moody/western/rustic ideas that you can find if you search. You need to provide more guidance on what it means to you.

The below photo is of an office - but the elements could be used in a non-office setting (minus the desk + add a bar area + tv).

Below is a garage that was turned into a man cave - but again, elements could be used in a room inside the house.

Probably a bit too much stone - but adding in some stone would look nice.

A bit more contempory feeling:

Do you have any inspiration photos?

great inspiration photos from dani! I'd stay away from dark paint, at least to start, as it will fight with the high ceilings and natural light. maybe look at the textures like the stone, wood, or corrugated metal, and see where you could use those to start bringing in that feel. but honestly, it's going to be easier in a more enclosed room...