You are right I should have clarified my example that at the beginning of words the phoneme ex is quite common and pronounceable. However at the end of words and not combined with an e there are few words that naturally occur in Spanish . There are some examples like Jumex or even Mexico that have an x not in the beginning of the word, but they typically have an e before them an aren’t pronounced as hard of an X as in the english word latinx. Perhaps this is more Mexican Spanish which I am more familiar with, different places do have different phonemes. But think of the diference between how native Spanish speakers pronounce Mexico and native English speakers. There is a difference in accent and less pronunciation of the hard x.