Exactly. The best choice of tires & wheels is a direct ruction of :
IMHO the 21" Arachnids are great for sunny SoCal... but your 19" Arachnid TS Sportlines are better for all-weather Colorado.
- the environment you're driving in (snow, rain, potholes, etc.)
- you style of driving: aggressive, casual, hyper-miler
Low profile 21" tires & wheels will ALWAYS outperform 19" tires & wheels. Look at ANY high performance sports car or road course race cars... they're ALL low profile tires & wheels. Think Formula 1 where budgets are non-existent and performance is KING.
But Tesla Model S is NOT a sports car... but 21" staggered Arachnids with super stick Michelin Pilot Super Sport tires definitely make it handle better... and hook up better in stop light races too.
I agreed with the first part of your post, but the second part is not always true. It is always risky using superlatives (see what I did there? ) All other things being equal, a smaller wheel+tire combo will weigh less than a larger one, and that's a good thing. Sidewall height is only one part to the handling equation.
I think it's fair to say the S with the plus or raven suspension is at least "sporty", though I also wouldn't classify it as a "sports car." I think it does benefit from tires with more grip, however, but some people would prioritize range and tire noise above that.
Also, F1 used 13" wheels up until 2021... Revolutionary wheels: Why F1 going 18-inch will change everything · RaceFans