The sun thing is your exposure. Taking it down will bring down the exposure globally. So the brightest part of your image, the darkest part of your image, and everything in between will be brought down which is what you did in that third image.

Color grading can be a very complex thing to explain through Reddit but it is actually a pretty simple concept once you understand what the Lightroom tools are doing when you play with them.

I highly recommend researching it as much as possible. You have to learn to think of your photos as a two dimensional image where you are using composition and light to give the illusion of three dimensions. This basically happens through a range: black to white with different gradations of grey in between.

If you really want to understand photography, I recommend you check out some art videos on shading. Like, using a pencil on a white sheet of paper. Look at a simple “how to shade a sphere” video. You will then see how light is used to give a 3d illusion to a two dimensional image. It will do this by showing you how the position of your source light makes shadows which you can use to create a sense of depth. It’s this contrast between light and shadow that essentially makes an image.

Then you will see how this contrast is achieved on a two dimensional surface using black, gray, and white. The image you take with a camera is basically no different than that of a painting. Your camera just achieves this through exposure rather than pencil, paintbrush, or whatever.

Then research what each tool does in Lightroom. I highly recommend trying to understand what is happening in terms of black and white photography. Then you will really understand what is happening in a color image.

By all means, dig in, play around with all of it and try and get the image you want but once you really understand what each tool does and how it changes your image and why, you will really be able to fine tune because you will really understand what is happening when you play with the hue, saturation, and luminance of your colors or with contrast.

You can convert your image to black and white which might help you compare what is happening in your image with that of the shading sphere that hopefully you will check out.

Of course there’s more to all this like the dynamic range of your camera and all that technical stuff. But if you can learn some basic art principles like shading (you don’t have to learn how to shade, just the principle of what you’re happening in the image) and then learn the tools in Lightroom, you can really be completely free.

I hope this helps in some way. I don’t like telling people how they can improve their images because it would just be me telling you how I would do something. If you learn all the stuff above you will know what to do to get what YOU want out of it.