A few language have national government agencies to regulate the language. For example, France issues official lists of French words to use rather than English words, and in theory government employees can get in trouble for not using words on the list. In general, “standards” issued by government agencies are totally ignored by everyone except their own staff.
Someone tried to invent a “standardized Yiddish” about 100 years ago, in part combining aspects from different dialects (vowels from one, consonants from other, syntax from a third). Thanks to the German, onlyoone dialect of Yiddish now is common (southeast dialect, as used by Orthodox Jews). All attempts to standardize English have failed though some historical events have tended to promote standardization (e.g. the southern dialect has been considered “wrong” since 1865, and for the most part the mid-western dialect is “correct”, note who did what at Appomattox for an explanation how that happened).
However living languages by definition have ever-changing vocabulary and grammar, and Yiddish is unusually flexible since many native speakers feel free to “borrow” words from other languages without thinking twice. The grammar also evolves (anyone notice that the 2nd person formal form is dying out, probably since Hebrew and English lack one, e.g. using “DU” to mean you is no longer ruden when talking to a person who thinks they are more important than you).