The mirror above the fireplace isn’t working, a nice art piece would be great there. I would declutter the mantle and think about larger/taller decor for better impact. In my opinion the room seems a little cluttered with lots of small things. Fewer, larger items make a huge difference. I can relate to the wanting every room to be perfect. Relax, slow down and make a plan for each space. Don’t move onto another room until you are completely happy with the way it looks.

You aren't showing enough pictures, angles of the WHOLE space for anyone to help you. Other than you need an electrician for the tv mount, and to reduce the clutter of tiny things. All the things, including tiny pictures on that wall adjacent to fire : )

Yes to chunkier candlesticks on the mantle or a similar arrangement of a few more substantial items. Don’t rush, develop the ideas and find the things that you love over time to create a personal space; there there’s no need to follow someone else’s instant recipe.

Aside from mantle decor: The lower half of the fireplace below the mantle is narrower than the upper half. It looks off balance and top heavy. The Emerald Green tiles sound lovely but they would accentuate the asymmetry. To remedy that, I would remove that 3-4 inches of baseboard on the angled section on each side and clad that vertical strip in your tile from wood floor to wood mantle. The upper and lower halves would be the same width. You could then even bring the tile floor-to-ceiling. Wouldn't that be spectacular? Then decorate mantle with white items to stand out.