Please post a photo of your metal wall art.

Sure you can paint it. It will be a solid color, as a base. Then you can add a color ( or two) in highlights with a brush, or wipe on/ wipe off with rags. My neighbor did a fake verdi gris on hers. looked great.
My mother used to use a product called run n buff. doubt it still exists.

rub and buff still exists

Trying to post photo. Not working.

There are a couple different options for you, you said you wanted to maintain the detailed areas and rugged portions, we would recommend experimenting with a thinned out patina mixture. You might have to get artistic and deliberate on your applications but it would be a fun task and you might be able to change the hue of the artwork. We aren't sure exactly what you are working with but patinas are also good for opaque metal design as well, if you'd like to completely transform your piece. https://www.industrialmetalsupply.com/products/metal-finishes

Here's an example of a patina finish on metal.

The Hampton Court Kitchen · More Info