are you open to changing the wallpaper? Or painting out the fireplace to better match the existing paper?

Once the colors jibed better, i wouldn’t add anything but a great piece of art

No-construction route: a chunky wood mantel is a solid call, and I'd paint the fireplace surround to blend with the wall so it stops fighting the room. Then add a big piece of art or a mirror centered above the mantel, and flank it with matching slim bookcases or a pair of low cabinets so it feels built-in. Keep styling simple, odd-numbered groupings, nothing too busy. If it's a gas or wood-burning unit, check clearance for the mantel with a licensed fireplace pro first.

Suggest aiming for a more unified/calmer, modern feel. Both the wallpaper and the brick’s color are hampering that. Paint the brick and hearth the same color as the walls and the brass surround black (use the appropriate paint). Add large art and plants to balance the wall. Inexpensive, easy and will make a huge different.

With the money saved, consider drapery (Ikea has nice inexpensive options), a calm rug and cushions, and even a coffee table.