Ah, Starbucks, home of weirdly huge coffees. Fun fact: since the popularity of flat whites in the UK, it's been much easier for me to get a coffee that's the strength and quantity that I like. An Americano is too big and too weak in all but the most hipster of coffee shops, but an espresso isn't enough coffee for a social drink. A black coffee in a flat white-sized cup is just right thanks (for some reason it's called a 'short black' or a 'long black' in places that recognise that this is a good drink, I assume as a calque of the Italian caffè lungo, which contrasts with just a caffè, which is an espresso). So I ask for that and responses range from just doing what I asked for to utter bafflement from the barista and ultimately a weirdly big coffee for me. Guess which one of those is the Starbucks response.
It's already weird that the smallest size they have on the menu is 'tall'. At some point, they introduced 'venti' as the biggest coffee - 20oz, which is a pint. A literal pint. Apparently there's now 'trenta', which I assume is 30oz, which is getting on for a litre. So those are size names which are specific to Starbucks, and you just have to know them but it's easy enough to work out that there's a scale of sorts. No big deal.
This Economist article talks about the language of Starbucks, saying that they 'refer... to macchiatos as 'marble' and mochas as 'zebra'', and putting this down to an effort to create an in-group feeling among its customers: having a language that you and your group know, being part of the crowd, being part of a community. It also says that
Starbucks even uses its own grammar: you say your size before your syrup, your preferred milk before your primary drink.
OK, we're in my wheelhouse now if we're talking grammar. And... I'm not sure what this is meant to mean. This really just describes the rules of English. If I wanted a large caramel soya latte then that's what I'd say. The adjectives go before the noun, in the order the author mentions with the size first, and the drink type (the 'head' of the phrase) goes at the end. I couldn't ask for a soya large caramel latte, or a latte caramel soya large, or anything else. I could ask for a large latte with soya milk, taking the milk choice out of the noun phrase stack and putting it at the end in a prepositional phrase, and I could do the same with the syrup: a large soya latte with caramel syrup. Notice that if I do this, I need to add in a new noun for soya and caramel to refer to, because I've removed them from their place in the latte noun phrase and put them in a different noun phrase in that extra prepositional phrase at the end (with syrup/milk). At a push I could even take out the size: a caramel soya latte, and make it a large one. But if I'm putting all the bits in the same phrase, modifying just one noun (latte), then they go in the order the Economist author says is special to Starbucks grammar.
If you want to create an eye-catching linguistics gimmick, you can play with words as much as you like, because we learn new words all the time and we can learn new ones. You can't really play with sounds or structures, though. Sorry Starbucks. Your grammar is nice but it's just English.