How can I improve my milky way photographs?

Your biggest challenge seems to be finding a place where the sky is dark enough. Light pollution is washing out the finer details of the night sky.

Beyond that, your lens seems to be poorly focused on the stars and is also exhibiting a considerable amount of chromatic aberration.

Those pictures you’re trying to reproduce are using mounts to cancel earth rotation, stacking of multiple images and heavy postprocessing. A tutorial workflow can be seen here: https://pixinsight.com/forum.old/index.php?topic=5516.0 Note that PixInsight is one of the few (commercial) software packages for postprocessing astro images, but similar postprocessing can be done with other software, too.

First ISO800 seems rather low, make sure the histogram is at least in the middle. Beware of burnt out (overflowing) stars, though.

Then you‘ve certainly captured RAWs, haven‘t you? If not, do so.

Then don‘t be shy with the knobs in Lightroom or what you‘re using. Astrophotography is at the extremes of what‘s possible and also needs extreme settings in processing.

Then the natural next step is stacking: Take multiple exposures and stacking them, e.g. in DeepSkyStacker or SiriL.

One further step then will be using a mount, that cancel‘s earth‘s rotation. For Milkyway have a look at LX2/LX3, Vixen Polarie, SkyTracker Pro or StarAdventurer mounts. If you’re on a budget, build a Barndoor tracker yourself.