There are quite a few Kingdom Cards that can create the game state to double-Province without requiring the use of any other Kingdom cards.* For example, Remodel. With Remodel and 4 Golds: play Remodel, trash Gold, gain Province, play three Golds, buy Province.
A few more cards can, similarly, triple-Province. Market: Play ten Markets to end up with a hand of 5 Golds, triple-Province with those $25 and 10 buys.**
Grand Market can, in the same way, quadruple-Province.
A hand of Candlestick Makers can, fairly simply, quintuple-Province using buys and coin tokens. Governor (EDIT: and City) can also quintuple fairly trivially.
What other two cards can generate a quintuple-Province on their own?
*"Double-province" meaning, get two Provinces on a turn without milling/sacrificing other VP cards.
**There's at least one more triple-Province card that isn't mentioned here and isn't one of the two answers.
***Of course I could be wrong about so many things! Maybe there's more than two.