You could try adding an adjective-forming suffix -i, then do /ai ei oi ui/ > /e/ in final syllables, then /e/ > [ə] > /0/ in final syllables. This would get you most but not all adjectives to end in consonants, and also get rid of final -e on other words unless it is restored by analogy. This sounmd change would also remove the -i itself.
I assumed for simplicity's sake that you had /a e i o u/ for vowels but almost anything similar will work; even /ii/ > /e/ is possible if you put it through an intermediate stage like [əi].
I dont think that a straight-up deletion of final vowels would occur in all adjectives and only in adjectives, however; sound changes arent generally restricted to one class of words. When they are, it's usually because of the influence of an adjacent affix or sometimes an adjacent word. I cant think of many natlang examples ... all that comes to mind is the changes that applied in most Germanic langs only to function words that were usually unstressed ... but I use this method myself in conlangs all the time.
_________________ Sunàqʷa the Sea Lamprey says:
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