I have a formatted string with 2 arguments but why I can't pass my function that returns 2 values?

I’m kinda new to Go (actually started yesterday) and I couldn’t get why these are giving me error

func first_char(s string) (string,string,string){
  var chars = strings.Split(s," ")
  return chars[0][0], chars[1][0]

in golang is possible to pass a multi-value returning function call to a variadic parameter only if you don’t specify the format. So for example fmt.Println(getInitials("lets go") will work.
See Spec: Calls

  1. You specify for this function return 3 string and your are only return 2
  2. In Go a string is a sequence of variable-width characters where each and every character is represented by one or more bytes using[UTF-8 Encoding so if you take one character from a string, that is not a string but a byte so you would need to convert it, so return string(chars[0][0]), string(chars[1][0])

Thanks a lot for help!