Suppose I have a tune; in this case "Only you and you alone" by the Platters and we have sheet music in the key of "C", (and we want to stay with that key) there is no 4 part vocal harmony in print or if it is in print it is not the key we want. Can I get a list of chords and depiction of the chords that fit with the note (the lead singer note) that I can use to build the chord for the parts ; in our case-STTB and retrofit into the song?
Yes, you can create four-part realizations from a chord sheet (you can even modify some of the chords if you're feeling adventurous). If your actual question is "how do I do that", you'll notice that this question has already been asked here, and has been closed as being too broad.
However, if you've never done this before, and you already found a 4-part harmony that's printed, but in the wrong key, it might be easier to change the key of that, rather than rewrite the whole thing from scratch. Or at least use it as a reference when writing out your own parts. Since most four-part harmonies are SATB (instead of STTB), I have a feeling you'll need to lower the alto part somewhat.