Where does “такой” come from?

такой (Russian) comes from Old East Slavic такъ, from Proto-Slavic takъ — such, such a (kind of), of that kind.

такой (Russian): such (a), such, that/this kind/sort/type of, those/these kinds/sorts/types of, like that/this/those/these; in the negative also: no such often translated as simply "that" or "this", meaning not only the specific thing in question but also any instance of that thing resembling it