I have been looking online for the UTF8 character table. And all I could find for subscripts were numbers 1 to 9 and some of latin letters.
I need to find S and B a
The authoritative reference on what characters there are in Unicode is the Unicode Standard. You can find the relevant information in the PDF code charts. The most commonly needed subscript characters are in the “Superscripts and subscripts” block. To get a full list, check the Unicodedata.txt file and search for characters with in their description. Beware that many of them are for specialized used, e.g. in phonetic notations, and may work poorly outside such usage, if the glyphs have been designed for the special use.