There's no absolute rule to say whether a light red apple manifests "coordinate adjectives" (the apple is both light in weight, and red in colour) or "cumulative adjectives" (the colour of the apple is light red; we know nothing about its weight). The elements in the coordinate form are often separated by commas or "and", but that's not bulletproof. You just have to use "common sense" to recognize which parsing is intended.

Your example is different. In my example, 'Big' is a size while 'red' is a color. As per the genre rule, it should be cumulative. It is used as a coordinate adjective. The other two as well are different genres. Tiny is a size, Cozy is an opinion.

"coordinate adjectives" just means consecutive adjectives modifying the same noun following. In the case of a big red apple, that's the normal sequence, as per the "Royal Order of Adjectives", which you obviously know about. That doesn't mean a red big apple is "ungrammatical" (in certain contexts, it might be the preferred sequence). And since "elegant" and "cosy" are more or less "opinions", those two would normally be an elegant tall tower and a cosy tiny cottage - but again, that's not unbreakable rule.

It's getting a bit silly, but if light red apple is parsed as "coordinate adjectives", you might refer to a light spherical red apple and a light oval red apple (both apples are light in weight, and red in colour, but they're different shapes). BUT if it's parsed as "cumulative adjectives" we obviously can't break the sequence light red - if there were two different shapes, they'd be spherical light red apples and oval light red apples.

I don't know why you are bringing 'light red apple.' Parsing 'big red apple' as coordinate doesn't necessarily mean you add one or more adjectives (like big bright/shiny red apple) and expect them to be parsed as coordinate. Isn't it?

I'd never heard of "coordinate" or "cumulative adjectives" before reading this question, but you seem to be asking how that "Royal Order" works when some adjectival elements are in fact "composite" (i.e. - light red may be a single adjective to be treated as a unit which defines a colour, as opposed to specifying two attributes (weight and colour). If that's not relevant to whatever you're asking, I'm afraid I simply don't understand your question.

That link was good even though it only talks about cumulative adjective order. Thanks for that!

Coordinate adjectives are of the same weightage or they don't build on one another. So we can interchange the order. Some examples: Bright, sunny day. Tranquil, relaxing beaches. Exquisite, hand-crafted jewelry. Delicious, homemade cookies. In most cases, they are of the same genre. But in the initial examples, they are NOT of the same genre.

I don't understand what you mean there. Nobody says sunny bright day - it's always a bright sunny day. If the rule you've learnt tells you "we can interchange the order" of that example, it's either an incorrect rule or you've misunderstood it.

...but you might find this chart interesting. I believe the "unusual" rise of a grey dull day is down to writers perceiving the day as both grey and dull, and thus thinking the order isn't so important. There are other factors, though, including the fact that dull grey/gray is a well-established collocation, however you parse it.

There is a group of adjectives called Coordinate adjectives. There is not much to understand about the rules as it is clearly stated in different sources. Being equal in weightage, the adjectives can be switched OR we can introduce 'and' between them. Whether Bright, sunny day can be included in that is the only question. There are hundreds of examples on the web.

If you do a search for "Bright sunny day" you have multiple sources that confirm it is of equal weight (coordinate) and that means it can be reversed. From a source: "The Reversal Test: Try reversing the order of the adjectives. If the sentence still makes sense, they are coordinate ones. Example: A “bright, sunny” day is the same as a “sunny, bright” day." PS: As for your comment "Nobody says Sunny bright day: Most people say "Tall dark handsome man" (cumulative and not like our examples). But it should be "Handsome tall dark man" as per credible sources. So we will stick to those sources.

Please note that in the "Handsome tall dark man," there SHOULD not be commas being a build-on adjective. This is unlike our discussion.

@brp7 Are you asking us for advice or telling us the answer? And do you actually understand the difference between the coordination and stacking of adjectives?

Did you not check my link? I may have overstated the case that nobody ever says sunny bright day, but it's so unusual I think most native speakers would notice it as "odd", and if they thought you actually wanted to learn English (as opposed to lecture native speakers about their own language! :), they'd tell you to only use bright sunny day. Commas are all but irrelevant in this context.

This website says that coordinate adjectives are ones that modify the noun equally - nothing about them having to be a particular 'kind' of adjective. By that rule, all your examples are coordinate adjectives.

@BillJ, I think he understands that from his comments. Do you have any valid input?

@FumbleFingers In that case, can we go back to our initial questions? Questions marked 1) and 2)

@KateBunting If they are of equal importance how come we have examples like Tiny Cozy Cottage, and Big Red Apple? Tiny is size and cozy is opinion. Big is size and red is color. Is that the same way we classify cumulative adjectives? So why do we classify it under coordinate ( equal weight) adjectives?

See this blog about the royal order of adjectives,. There are always exceptions to "rules" about English, but the big red apple fits the standard "Quantity or number, Quality or opinion, Size, Age, Shape, Color" pattern anyway (size comes before colour). A more "real" exception might be the big bad wolf, since bad looks like a "quality or opinion", so it should come before big (obviously "size").

...and despite this usage chart, I can't even claim that nobody ever says the bad big wolf either. But people will definitely notice if you mangle that one up!

@FumbleFingers Thanks for your time and useful links even though they don't answer our question. I have upvoted your comment.

Tiny and cosy are both adjectives describing the cottage; one doesn't depend on the other. The website I found says that cumulative adjectives are expressions like bright green dress, where bright describes the shade of green.

@brp7 What do you mean by "our question", and by "I think he understands that from his comments"? There's only one of you isn't there?

@BillJ Still no valid input?

@BillJ "After reading his comments, I think he understands whether I am asking a question or providing an answer."

@brp. Never mind; you are clearly confused by all this.