I saw a passage "this doesn't mean to get riches and honors." 'rich' is an adjective but 'riches' is a plural noun according to the dictionary. Are there any other examples where an adjective becomes a noun by adding suffix '-s' or '-es'? or 'riches' is the only case?
In fact, yes; good point. You can turn many adjectives into pluralized nouns:
The yellows (the team in yellow t-shirts)
The dispassionates (phlegmatic people)
Your smarts (your know-how)
Hello, my pretties (a pimp's greeting, I suppose)
Put your briefs in the hamper (underpants)
The indolents (the rentier class)
Some you have to do additional work on:
Fasties, wiseguys, etc.
The only ones I can think of are "green" (the color) and "greens" (meaning vegetables), "red" and "reds" (communists) and "blue" and "blues" (feeling sad).
Hillary Clinton quite famously — or infamously, depending on your political bent — did so during her run for the office of President of the United States in 2016 when she said:
"You know, to just be grossly generalistic, you could put half of Trump’s supporters into what I call 'the basket of deplorables.' "
In the above, she used the adjective "deplorable" as a noun for a deplorable person and then pluralized it. Note that pluralizing it with an "-s" is not required. She might just as readily have called such a supporter a "deplorable," but then plurality isn't innate to the meaning being conveyed like it is with "riches."
Incidentally, using "deplorables" and using "riches" (were "riches" not already a plural noun that means the pluralous treasures and caches of money, hence "riches" being plural, associated with wealth - see def. 3 of 3) are examples of a type of rhetorical device called a "metonymy," meaning not only can you do that, but there's even a word for it.