It is known that in most King + Rook vs King + Pawn endgames, the person with the Rook is playing for a win. Typically side without the Rook courageously marches his King and Pawn up the board in the hopes of forcing the enemy to sacrifice his Rook to stop the passed pawn from promoting. However, exceptions always exist and in some unique cases, the person with the pawn can try to win!
Now we have another interesting position with White to move. Is this a win for Black or can White draw?
As you can see, extraordinary K R vs K P endings can occur and their result can be different than what your instinct might tell you. Always have an eye out for endgame tactics such as underpromotion and sacrificial stalemate and be sure not to take these endgames for granted! Tactical bombs can exist in endgames too!
With that said, keep in mind that over 95% of K R vs K P endings are not so extraordinary and typically are either drawn or won for the person with the Rook.
Wishing all the readers a delightful journey to chess improvement.