add button like escape or shift

how do i add new keys to unity?? like shift escape

becouse i want to use the esc button for when i press it my game willgo to a gui like Options gameplay Exit game thanks coud not find it on unity answers srry

You can assign new keys in the input manager and use the Input-class. Unity recommends to use this, but for special keys that should not be able to be changed by the user like "Escape" use:

if (Input.GetKeyDown(KeyCode.Escape)) { /* Do something */ }