You can use the bounding box with the Lattice node to create a deformation cage for the input geometry.
Subset of geometry to bound.
The type of elements referenced in the Group field.
Keep the input geometry.
Create When Bounds Empty
If there is no input geometry or the specified group is empty, a zero sized bounding box will be created at the origin. Turning this off will cause an empty geometry to be created instead.
When this tab is selected, it will compute the bounding box.
Number of divisions along xyz axes.
Places diagonal crossbars in the divisions of the box.
Oriented Bounding Box
Orients the bound box to the axes of the input geometry instead of the world axes.
This option only works on primitives with vertex hulls, such as polygons or meshes.
When this tab is selected, it will compute the bounding sphere.
Poles of sphere align with orientation axis.
Use a more accurate (but slower) bounding sphere calculation.
Lower, Upper Padding
The computed bounding box or sphere is enlarged by these padding values. Note that in the case of spheres, non-uniform padding values will not guarantee the resulting sphere still contains the input geometry.