How high off the ground is your mattress? Does the headboard go down and meet the frame, or is there blank space there. The box spring usually doesn't show that much. You can get low profile box springs. All this should be carefully measured BEFORE you purchase a bed. This one may not have been the best choice with your mattress.

You can also buy box spring covers like this.

I’ve had an upholstered bed last 10 years and don’t use a box spring. I remember I knew this before I purchased so must have been disclosed in description or shown in the online photos.

low profile box springs are pretty inexpensive; I think you can get them from Costco, and that will solve your problem I think......look them up on line. Or mattress stores have them too or try craigs list etc. the low profile are about 6 inches or less tall.....2 x 4 lumber might work too to fit into the frame of the bed.

Read the specs on your new bed frame. Does it indicate you need a box? Compare those specs against the recommendations from your mattress maker. Do the bed frame specs satisfy the needs of your mattress? If so, ditch the box springs. I recently abandoned the box springs for a frame with an upholstered headboard and it’s worked out well for me. This looks to me like you need to ditch the box spring.

Beds which are platform beds don't use a box spring. How is your box spring or mattress supported? Typically most mattresses need to be supported by either a box spring or a platform.

I purchased a new mattress fairly recently and none of the mattresses required a box spring nor was I asked whether I needed one. I have an adjustable bed frame which is in essence a platform bed. Obviously an adjustable bed can't be used with a box spring.

When I got the new upholstered bed I also got an adjustable bed frame and new mattress. I love the adjustable bed frame as I do almost all my reading in bed. My adjustable bed has a special adjustment for pitching slightly forward for the perfect reading angle.

I don't lean against the headboard. That would seem at least to me to be somewhat uncomfortable as I would be at a really extreme angle. I don't think I could maneuver to use the headboard like I was sitting in a chair.

You can purchase a low profile box spring. There are also box spring covers and a longer bedspread/comforter which will help also,

Others are correct that a platform bed frame does not require a box spring.

I purchased a traditional boxspring and mattress and frame this spring and found that the assembled height of the bed was higher than my butt cheeks - since I didn't want to use a step stool to get into the bed, I needed to lower the height. The low profile choice was still higher than I wanted, so I simply disassembled the box spring and removed the wood risers between the two platforms. The foundation fabric cover was easily placed back over the foundation, but the paper like backing on the bottom of the foundation tore, so I replaced that with an old sheet I had in my basement. You attach the fabric with a staple gun.

Knowing the height you want is the first step in figuring out the best solution.

We have a very similar setup- I bought a matlasse box spring cover like the one that @deeinohio linked and it looks great.

Looking at your pictures it seems like the headboard is appropriately level with the top of the mattress. You want the bottom of the headboard below the top of the mattress.

Given that this is correct the issue is the size of the comforter. I don't know if manufacturers haven't kept up with the mattress makers, but it does seem that many comforters are simply too small to adequately cover the thickness of today's mattress. I actually buy king sized comforters for my queen sized beds and feel that the proportions are better (I don't get expensive comforters because my dog is allowed on the beds). I also remember having to special order deep pocket sheets when I bought a mattress that was 12" thick. Now standard sheets fit a 12" mattress and you deep pocket sheets are found in every department store.

I just pulled up a King sized comforter on Macy's

Look at the depth of the mattress on the ad. - not the thickness of my new mattress!

The dimensions of the comforter are 104x88

The dimensions of the top of your mattress are 76 x 80

So you have 8 inches longer than your mattress (not designed to go to the very top of the mattress) and 28" wider than your mattress (14" on each side") The drop will be slightly less - so probably 12" drop on each side.

If you have a 12" mattress this bedding will just cover the mattress and leave no coverage for the box spring.

OP has stated her bed is King size

First, get out a tape measure and measure the width and length, both the top and the sides down to the floor. You'll have the dimensions you need. Then google "oversized king bedspread" to come up with ones that will come much closer to the floor. One of the results turned out to be 118"x122": https://www.brylanehome.com/products/florence-oversized-bedspread/300694294.html?affiliate_id=049&affiliate_location_id=01&utm_medium=ps_pla&utm_source=google&utm_campaign=Shopping+-+Smart+Shopping+-+Catch+All&utm_content=Ad+group&utm_term=--&gclid=Cj0KCQiAh4j-BRCsARIsAGeV12DQEPwc0-1lKQayF9feYImgTWeTcUyiQI1dyVotddIa7c-0MnCzJgAaAqFHEALw_wcB&gclsrc=aw.ds

There are plenty of others, however, so you should be able to find something you like without having to replace the box spring.