Well, if you want to say something like "She works because she wants to", that would be "Она работает, потому что хочет"
"так" is a pronoun paired with the interrogative "как" (how?) and means "so, this way". Naturally, "do it this way", "do it like this" and just "do this" are pretty close in meaning.
The question is what you mean by "She wants to", i.e. where you think you would use it.
Thank you for the explanation of " так" and "как".
We would answer "because she wants to" to a myriad of questions about why she is doign anything.
"Because she wants so" is just not standard spoken English. You could say "because she wants it to be so" or "because she wishes it to be so", but my mind just doesn't process "because she wants so" as a complete sentence.