application/x-www-form-urlencoded and charset=”utf-8″?

1. There is no charset parameter defined for this media type.

2. For the encoding guidelines, see https://url.spec.whatwg.org/#application/x-www-form-urlencoded .

The application/x-www-form-urlencoded standard implies UTF-8 and percent-encoding.

Though:

A legacy server-oriented implementation might have to support
encodings other than UTF-8 as well as have special logic for tuples of
which the name is _charset. Such logic is not described here as only
UTF-8 is conforming.