Hi,
A solution may be creating a Preset Spatializer Effect (FMOD Studio | Glossary - Preset Effect) which uses a Global parameter connected to the height of the camera which automates (FMOD Studio | Authoring Events - Automation and Modulation) the min max override of the spatializer. The values I have used are just an example. Then using the preset spatializer on all the events you want to be affected by the height of the camera.
You can change the parameter value in code using FMODUnity.RuntimeManager.StudioSystem.setParameterByName()
Hope this helps!