I don't know why it didn't post. Here goes.

Can you take a photo from farther back? We’d need to see the whole wall and ideally the whole room to be able to help. Thanks.

Do you think it makes a difference that your mortar and brick are all one color while mine are red and offwhite for the mortar?

You could mock up the look with cardboard and a tester paint to see if you like the effect. It looks like the hearth has been painted to match the brick. Is there any chance you might have some of that paint around?

That predates me I'm afraid. But thank you.

I’ve attemped to mock it up. I like the way the mortar defines the brick pattern, and I also like matching the mantel to the hearth.

What's going on on the sides of it? It looks like it's protruding into the room quite a bit. You'll need to figure out what happens on the sides at the same time. Can we see a picture? The niche to the right seems to need something. It would be a good idea to figure that all out at the same time. Do you have any plans for that? Is it a working fireplace?

A fireplace store would be able to help you with the mantel. I suggest a tile for the floor in front of the hearth, perhaps a slate or slate look tile depending on your decor which we don't see in your picture.

Nonworking fireplace. We were planning to keep the tv in the recessed area to the left on a smaller stand

If it's a nonworking fireplace the mantel can simply be done in wood and place candles in the hearth.

Thank you but we're only doing a shelf.