I would paint the wall that the mini split is on White, so it disappears into the wall.

hang a large framed piece or mirror over the cabinet, centered at eye level just as you would any picture.

Hang the ship image, don't lean it. The TV looks especially high for comfortable viewing.

Lyn’s suggestion of white paint sounds good. Framed art over the cabinet might also help to pull focus away from the heat pump. Agree the TV looks very high. It does look like a nice space. I like the brick wall.

What Lyn said …. other than hanging the art I wouldn’t ”style” the mantle .

I like your rug! Can you share the brand/model?

Hang the painting over the mantle. You don't really have the room for styling anything on it.

The TV does look a bit high.

I used a 75" Samsung The Frame TV with a DecoTV frame over my built-in, so I didn't have a black hole on the wall when not watching TV.

AS it's a new room I doubt you're going to paint all that cabinetry or the walls. So I would ignore the mini split it is what it is. Style the cabinet under it as suggested by @simplynatural. Hang the art. Add to the mantle as suggested. And lower the TV. The dark chairs are also throwing the vibe off but I'm guessing they're probably new. Put a light color throw - from the rug background over the backs to tone down the darkness. It is a lovely room Enjoy!!

As you can see, the green cabinets do match the rug.

Fredericke Tufted Wool/Cotton Performance Oriental Rug in White/Blue/Yellow https://www.wayfair.com/rugs/pdp/bungalow-rose-fredericke-tufted-woolcotton-performance-oriental-rug-in-whiteblueyellow-w110692737.html?piid=235450783

Here is the rug and another view

How about an Etsy enclosure for the mini split and a hidden art light?

I would just ignore it & decorate above the cabinet, nothing to enhance it, I definitely wouldn’t want to draw attention to it!

Such a lovely room! I really like how your rug pulls all the colors together. And the colors look cohesive together, even the green cabinets. Go color!!

I am not an expert or pro but something about the ship painting is jarring in this space with the lovely plants and earthy colors. It gives off a different vibe, is the only way I can put it. Maybe some small scale patterned drapes on the two windows by the fireplace?

Painting that wall to match the split AC sounds like a great idea. Enjoy the new space!

I think the TV and the ship picture are hung too high . Lower them which will mean moving the ship pic from there to another wall where the center of the art is at 60-65" from the floor . No more pattern in the space , the brick, the rug and some pillows are just right.Below the heat pump you need no living thing so nice pottery is a perfect choice. How about the ship by the piano?

How is it that the fireplace is sized to heat a great room? The scale of this element is jus too large for this small room.

To start off, let's call the heat pump what it is...a ductless split. It is a great invention and you just live with it. After a while, you won't even notice it. You could add a shelf above it.

You want to have a deeper shelf, to allow space for air flow.

As for the ship...colors are good, frame matches the mantel. Try hanging it on the wall so that a couple of inches of wall color separates the frame from the mantel.

The room is great! The ship painting will not work over the mantle. Note what @Paul F. did instead. Find a different place for that painting.

Ignore the duct. It’s part of human life. Or, again, look at Paul’s idea for covering it.

It wouldn’t have been my first choice for size of art for above the mantle but I think you can make it work by adding some decor to help it fit better with the space.

The cabinet just needs some taller accessories above it to fill in the space between it and the heat pump.