Adjectives appear after the nouns they modify. This is based off of Peterson's analysis of the text in the books.
Adjectives decline based on number in certain situations. For example in singular with an inanimate noun you would say alegra haj (a strong duck) but in plural it would be alegra haji (strong ducks). For animate nouns you would instead say rakh haj (strong boy) and rakhi haji (strong boys). Here we see that not only the adjective declines but also the noun which we didn't see happen for inanimate nouns.
Comparison is declension of adjective that determine to which degree the adjective modifies the noun. For example hot, hotter, hottest in English. In Dothraki this is done by adding certain circumfixes or suffixes to the adjective. Dothraki also has a set of comparison in the negative which in English is only possible with the construction less or least or by switching to an adjective of the opposite meaning.
|afazh (hot)||asafazhan (hotter)||asafazhanaz (hottest)|
There is also declensions for negative comparison that are a bit different.
|osafazh (not hot)||osafazhan (less hot)||asafazhanoz (least hot)|