Changing focal length does not change the relative size of object. Only changing the camera position does that. The examples you see online change the camera position. Digital zoom or physical zoom makes no real distance to the geometry (other than lense distortion, but that's not really a factor for long lenses)
I suspect this is physical 1000mm. The 3000 mm might be optical, but the change in quality mademe suspect not. But that could be low light. I'm unsure. Here's the 3000mm scaled to 1/3, inset over 1000mm,
It does seem a lot more detailed, which suggests optical 3000mm. I suppose that's not that unlikey, as my Nikon P900 does 2000mm equivalent. But also the. extra detail could just be because it's using more sensor pixels.
And as someone mentioned, the blanking between the shots suggests an optical change, not digital.
We'd need the exact model, and spec sheet