Each option shown at its easiest case and its hardest: an object that fits on screen, and an object so large that none of its edges are on screen. The second column is the one that decides this, because it is where a bounding box stops carrying any information at all.
The outline that exists today, pinned to the view when the selection runs past it. The frame itself becomes the message: what you selected continues beyond the screen.
The object carries its own state. Its silhouette breathes and it takes a soft terracotta wash, with no bounding box anywhere.
A flat terracotta tint on the object, plus chevrons on whichever edges of the view it runs past.
Animated dashes running along the object's own outline rather than around a box.
Four short brackets at the selection's corners, clamped to the view, over a barely-there tint.