The word <king> is spelled with an /ĭ/. The vowel is followed by the digraph <ng>. Because the /n/ is a nasal sound, the vowels around it are often distorted, and the /ĭ/ sound tends to be distorted. The word <king> is an example of a closed syllable, which often makes the vowel sound short.
The word <kind> is also a closed syllable. However, you may notice that the vowel in this word is the long sound /ī/. We have a spelling rule to explain why this vowel is a /ī/:
I and O MAY say /ī/ and /ō/ when followed by two consonants.
The <i> in kind is saying its long sound /ī/ because two consonants follow it.
Note: the spelling rule state that <i> and <o> MAY say /ī/ and /ō/ when followed by two consonants. This does not mean they will say /ī/ and /ō/ all the time before two consonants.