Check out example codes for "explosion godot". It will help you in understanding the concepts better.

Code Example 1

I'm not an expert with 3D games, I focus mainly on 2D games, but I think this should work:
1. After exploding get all objects in the range of explosion
2. Cast a ray to each object in the sphere
3. If the raycast is sucessful and nothing is in the way apply force to the object in the direction from explosion and multiply it with "1-(distance to object)/(explosion range)"

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