To use the Transition Modifier, append the node tree to your current project or add the file to your asset library. Once added as a Geometry Nodes modifier, set either a start or end transform and then animate the factor value in the Animation panel. The middle transform can be used to arc the motion.
The file uses the Menu Switch and Index Switch nodes, so be sure to use it in Blender 4.1 or later.
For the full explanation of how it works, watch the tutorial on how it's built: