JIS
Converts single-byte (half-width) ASCII or katakana characters to double-byte (full-width) characters.
See https://wiki.documentfoundation.org/Calc/Features/JIS_and_ASC_functions for a conversion table.
JIS(Text)
Text: the text string that contains characters to be converted.
Applying the JIS function to a string composed of double-byte characters will return the input string without any modifications.
=JIS("LibreOffice") returns the string "ＬｉｂｒｅＯｆｆｉｃｅ". Note that the returned string uses double-byte characters.
=JIS("ﾗｲﾄ") returns the string "ライト", which is composed of double-byte characters.