As volumes use BSP and BSP cannot be recomputed at runtime, the short answer is no.
The long answer is internally, nav volumes in particular don’t really require to be BSP, it just happens that BSP brushes provide an easy editor-driven way to define volumes. The actual struct doing the work is FAreaNavModifier, and it can accept a cylinder shape, a box shape or an arbitrary convex shape. Add the INavRelevantInterface interface to whatever actor you want to modify nav volumes with, then in your implementation of INavRelevantInterface ::GetNavigationData, you can create your own FAreaNavModifier and work from there.