Press and hold the Bixby button on your S10—it's on the left, below the volume buttons—and Samsung's digital assistant Bixby rumbles to life. You can't change this, but you can change what tapping or double-tapping the button does. Open Settings, pick Advanced features, then Bixby key, and you'll be able to choose an app. You can only have one custom shortcut assigned to any given app: either a single or double-tap.
