The trick is that most of the magic comes from the hands, not the brain. When I self taught calligraphy, I spend a long time just practicing drills. Pages and pages of lines, circles and isolated letters, where I was honing my muscle memory to be able to keep the pen at the correct angle throughout a stroke, or to make a stroke quickly enough that it looks smooth and not wobbly, but slow enough that it was still correctly aligned.

The brain-knowledge came afterwards. That's why, even after years of not practicing calligraphy, I'm still decent at doing some halfway pretty writing. Whoever wrote the phrase in the OP must be at this point too, because writing in snow on a car window will obviously use very different hand and arm movements compared to writing on paper.

I also futilely spent a lot of time trying to write in a pretty manner when I was in school. I eventually gave up and felt like someone like me, who is not particularly artistic, just isn't cut out for it. When I actually picked up calligraphy, some years later, I clicked with it surprisingly well precisely because I'm not an artist. It felt more like a technical skill, and I enjoyed the zen of just following the instructions for a particular script, and doing the drills.

I realised that part of my mistake in school was that I had been trying to jump straight to the level of being able to write in a decorative way. I only got good enough that I could do freehand, decorative style lettering when I had become proficient in 3 or 4 different calligraphy scripts. The only reason why it feels like the "writing" -> "art" conversion part of your brain doesn't work is because it needs to learn through your hands.

If you'd be interested to give it a go, a pen that I loved learning with (and still use today whenever I want to be a bit fancy) is the Pilot Parallel. They come in a variety of sizes and are a super accessible way to be able to start learning a wide variety of scripts without the stress of things like dip pens. The swirly writing featured in the OP would tend to involve using a flex nib, which does typically require dipped ink, so I didn't even touch that stuff for years, despite being enamoured with the pretty swirls. This is the book I learned from, and if I were to go back and try to regain some of the "hand-knowledge" I've lost over the years, this is what I'd return to.

I liked doing calligraphy because it allowed me to feel artistic without actually being all that creative. It's also pretty great for gifts. "Half uncial" is pretty similar to the script used in Lord of the Rings, and isn't too hard, so I used that to make a thing with one of her favourite lines from the book. Another friend got a postcard with "FUCK" written in fancy, gothic capitals. It took a while to get to that point, but it was pretty cool once I was.

Have you thought about taking calligraphy courses? That could be fun!