https://www.pcgamer.com/eliminate-your-enemies-with-stealth-in-sekiro-shadows-die-twice/

In Sekiro you play a shinobi on a quest for vengeance. An army of enemy soldiers and monsters stand in the way, but they can’t fight you if they can’t see you. You can battle everyone face to face if you want to, but why risk your life when you can stealthily avoid enemies, or kill them instantly from the shadows?

The dark fantasy world of Sekiro has many places to hide. Crouching in the long grass makes you practically invisible. You can use this position of safety to observe enemies in an area and look for routes past them. If you catch an enemy in the long grass you can kill them instantly with a Deathblow finisher from stealth.