I think your space looks very nice. If you'd like to change things around your fireplace, I would consider simplifying your mantle decor and replacing it with a larger piece of eye catching art with a frame that doesn't blend into the wall. Or you could paint your fireplace surround. I think an accent wall will chop up your room too much.

You have a beautiful home in a traditional style. An accent wall may be a more modern/contemporary look than would be appropriate.

Paint is cheap if you are going to DIY. You could try it, and repaint if you don't like it. Just make sure you have the original paint color so you can repaint back to the original if you don't like the look.

Another thing to consider is the white color of your trim. Is it white-white-white pure bright white, or is it an off-white? If it is an off-white, a brighter, pure white would give you more "pop" without changing the wall color.

Another thought to draw attention to the area is adding molding above the fire place to draw more attention. Search on "molding above fireplace" for examples.

Another thing to meditate upon is something I have read several times on this forum. Is that a mirror above the fireplace? A mirror in a room should reflect something beautiful and interesting, such as a beautiful scene outdoors, or a sculpture, clock, or some other beautiful object. What do you see when you sit and look at the reflection in the mirror?