Spaces have bounding boxes that visually represent their extent. In the respective panel in the Inspector, you can control whether a bounding box is shown or not, and whether it blocks the selection of content inside of it. The latter options can be used to “lock” content in spaces.
Bounding boxes are selectable and movable using a mouse. On touch devices, you can additionally use multiple fingers and gestures to rotate spaces around their vertical axes and adjust their scales. On XR headsets, you can interact with bounding boxes by selecting them using one or two controllers. Using only one controller, you can change the position of the content in 3D. Using two, you can rotate it by gyrating both controllers relative to one another, or change the scale of the selected content by moving controllers apart or together.
An empty bounding box of a space.
The Box Settings let you choose whether the bounding box is displayed and whether it blocks the selection of its content via direct interaction in the 3D workspace.