Yep. The letter K is basically a concession of the Latin alphabet to make some more sense of Greek loanwords, where the letter K is originally from, following a series of pronunciation shifts. But C is the Latin K, so words of Latin origin (the majority of vocabulary in Romance languages like Spanish) will normally only use C for that sound.

K is more useful in languages where the soft C has entered use (like French, Spanish, English, and others) just because K is always hard and makes it easier to define the pronunciation of loanwords that may otherwise encourage the wrong pronunciation when paired with certain vowels (kite, cite, and site all being different words in English, for example).