Here is the issue, well there really isn't an issue.
By default, desktop backgrounds are set to "Fill Screen" which means it will scale the image proportionally until the entire screen is filled. You could set it to "Stretch to fill screen" which will fill the screen but it will also distort the image.
Before installing the web drivers your monitor was not running its native resolution, you can see this by booting with the flag nv_disable=1. Most likely the monitor will be running in 1920x1080 and the image will look like it is fitting but really it is being stretched.
Here is that image with a 21:9 Photoshop crop tool, you will see the image inside the box matches your screenshots exactly
Thanks again for your input. It really makes a lot of sense now when you explain it in that way.
After reading your response, I decided to do more research and found that my monitor is not running its native resolution, because when I boot into clover and go to "about clover", my screen resolution is set to 1920X1080. I did find some instructions to try to change this to my native resolution, but no luck. I made some changes to my plist and I have CSM enabled in my BIOS, but when I install the CSMvideoDxe driver in clover, my resolution changes to 800x600 in clover.
Is there a way to change my monitor to its native resolution in clover before booting into High Sierra? If so, could you please advise me as such. I will include my plist for your reviewal so you may see the settings I currently have.
By the way, I also downloaded the original High Sierra wallpaper and sized it to 2560x1080, then set it for my desktop background and now I have the full picture. But I still feel that my monitor is not running at its native resolution.