can a king capture a king in chess
It is not meaningful to assign a value to the king relative to the other pieces, as it cannot be captured or exchanged. In this sense, its value could be considered infinite. As an assessment of the king's capability as an offensive piece in the endgame, it is often considered to be slightly stronger than a bishop or knight -- Emanuel Lasker gave it the value of a knight plus a pawn (i.e. four points on the scale of chess piece relative value) (Lasker 1934:73). It is better at defending nearby pawns than the knight is, and it is better at attacking them than the bishop is (Ward 1996:13).
King (chess)