Lose a ko to win the game
One technique to seal a game when you are in a winning position, is to create a ko in the opponent's large prospective territory, preparing to lose it and play elsewhere twice. The prospective territory becomes effective territory, while you choose an area to play twice. This simplifies the game. Given your being ahead before the exchange, the simplification is very likely to result in a clear advantage. The idea of making a ko when ahead, for simplification, is perhaps not intuitive, since a ko feels inherently complex to the amateur, but we can see it a lot in professional play, in particular in the games of Go Seigen and Gu Li.