From what I can see of the LR the sofa looks very traditional so I think I would stay with the white surround in your inspo pics

Sofa being replaced. Trying to update the look overall. Thanks for the thoughts.

@lizakirk - You have to go by your town's code for a fireplace redo. There are specific requirements for how far away your mantle/wood can be from the firebox therefore, no one can give you proportions unless you have your town's code posted as well. It's also good to know the dimensions of the actual firebox. Your kitchen is lovely. It is current without being trendy. It has a wonderful aesthetic, and I would remain true to that in your living room. A white mantle and the herringbone tile will look great. Get the requirements from the building department and post here for help. I am attaching a photo of my fireplace for reference. My mantle is 82 inches wide and 55 high.

Like the idea of the white mantle and surround you're considering (inspiration pics) but not a fan of the kitchen tile on the fireplace idea.

Whether or not you have an insert in the firebox can make a difference in what you can or cannot do with your fireplace and/or if it is for burning wood or is a gas burning or electric fireplace . If you cannot lower the mantel to where you want it any other way, you might be able to "lower it" visually by adding a board against the brick beneath the mantel or boxing around it, thus making it thicker and/or larger. Know the local code and follow it for both legal and safety reasons.

https://www.google.com/search?q=small+white+fireplace+surrounds&source=lnms&tbm=isch&sa=X&ved=2ahUKEwj-l_y7hcPmAhVGQ6wKHWrYCaoQ_AUoAnoECA0QBA&biw=1326&bih=617#spf=1576804234889

You have stainless steel and black appliances in your kitchen. In lieu of tile, you might also consider covering an area around the firebox with a stainless steel surround w/stainless steel surround/cover/doors/screen, then adding your favorite white wood mantel and/or surround.

https://ecofirefeatures.com/Fireplace-Surrounds.html