We pick that 'knowledge' (of syntactical rules) up instinctively during language acquisition, in the same way that we 'learn' that in English determiners (e.g. definite and indefinite articles) precede their nouns, hence 'the dog' is 'English', 'dog the' is not. We don't need to know consciously that English has that syntactical rule, but it does and we -- especially if English is our first language -- do 'know' it and simply follow it. We can't say 'why' 'dog the' is wrong, necessarily, but we know that it is. The nerdish among us find it interesting to understand 'why'!

So, the order of adjectives when two or more precede a noun? Basically, 'general to particular'; 'opinion to fact', etc. It is much more complex*, but that's in essence why we hear -- or should hear -- 'her amazing new black bike' as ok, but 'her black new amazing bike' as somehow 'wrong' or 'awkward' -- again, especially if English is our first language. As with your examples: 'black big dog' or 'suede old coat' would just sound 'off'.

In large part 'learning grammar' just is bringing those syntactical rules that govern the use and order of words in a language (any language) to consciousness, so to speak.

*If further interested in adjective order in English, here's a useful chart from Cambridge: https://dictionary.cambridge.org/gra...oogle_vignette