How can I make over this wall?

Have you thought about any ikea hacks for a long wall like that surrounding a tv with shelving. I have found a couple of ideas for you. Depends on how much work you want to put into it;)

https://www.hometalk.com/diy/build/furniture/diy-built-ins-with-ikea-billy-bookcases-29141456

https://www.hometalk.com/diy/basement/furniture/design-and-decor-446277

Add a bit of decor on either side of the television. Small wreaths, cotton stems, perhaps your initials (his on 1 side, yours on the other) in vinyl, or what would go with the theme and style you want to have. After adding that, take another photo from a straight point of view rather than angled to decide if you need something to the left of the frame. Perhaps a shelf.

On the wall above the loveseat, I would hang a large wall clock.

It looks like that TV is way too small for that area or vice versa. The walls would look so much better with a few pictures placed spaced out evenly. Some people really overdo it but on the blank wall I would place one big photo or one big one in the middle with two small pictures above and below diagonally

Damaris: you could put three floating shelves on each side of the tv. ...they come in various sizes and styles!

https://www.target.com/s?searchTerm=floating+shelves&facetedValue=5y761

How about painting it an accent color?

I agree that the tv looks far too tiny where it is. I also agree that it depends how much money or time you want to put into things. I think using peel and stick or plywood cut into planks and nailed in with a herringbone pattern would look terrific and then the tv would also look fine.

For the wall behind the couch I would put up one large piece of artwork. You can find a poster you love and mount it to plywood with some simple framing around it or order a frame online. You can make art from fabric, paint, a shower curtain. You'll find something great! 😎

I would take off the trim/shelves. New coat of paint/accent color with wall art and hang pictures.

The number one issue is that the edges aren't straight and clean. A strip of quarter round, shoe moulding or crown/base would really make a huge difference.

Adding some crown molding would also help to finish off the look. Good luck!

I think the wall would look better without the wooden shelf that is there, but since you are probably not willing to remove it, I would take the pictures off of the top-they crowd the ceiling and hang them along with more items around the TV. I would also hang instead of prop the pictures on the other shelf. Use the shelf right above the TV to put a few decorative items (not too many) like a colorful candle (don't burn it on the shelf), a pretty piece of pottery or a vase. You can stick these items to the shelf with adhesive putty so they won't slip. Also add some 3-D items around the TV like a flat back metal basket, raised plaque, even a pretty plate. Items like this can be found in thrift stores and add a lot of interest to a picture wall.

Paint terracotta pots