Support for Delta Updates in Unity

Are there any support for Delta Updates in Unity? (iOS apps)

No. Even android that you need to split your app into OBB file you must always send everything again.

The solution is to implement your game in a way that you “load assets from remote source”.

Unity have some support using asset bundles, but you can always load plain texts and build your assets (model, textures, materials, etc) dynamically from them.