Just sharing because finding this info is really difficult to find.
First, there are a number of nodes dealing with camera shakes. None of them return you an actual reference to the shake, so you can’t do anything with it after creating it.
In order to get a reference to the created instance of the camera shake, you need to use the Player Camera Managers Start Camera Shake node:
This is the only node I can find which returns reference to the shake, which then allows you to update it later via blueprint.
I still don’t know if there is a way to adjust any other properties besides the scale, but I suppose it may be fine to just create a different camera shake and layer them for effects like that.
If epic wanted to share some broadly applicable and useful info, I think a deep dive into camera shake best practices would help practically everybody. There are tons of camera shake stuff in the engine but very few resources and they tend to only show the barest bones setup.