I see no way to scale an entity with a hover effect.
The closest I can find is by using HoverEffectComponent with a shader hover effect. Maybe I can change the scale with a ShaderGraph, but I cannot figure out how.
Is it possible to use a scale hover effect on an entity?
You can indeed use a HoverEffectComponent with a shader graph. You can use the node HoverState and feed the values into a GeometryModifier. However note that it will only affect the rendering and won't affect the colliders used for hit-testing.
If you would like RealityKit to provide an easier way to achieve this, please file a feature request on http://feedbackassistant.apple.com and share the ticket ID here.