How to make object visible only inside another object? I am not such an expert, but also not completely noob and want to make animation like in this template: https://www.storyblocks.com/video/stock/new-business-corporate-promo-hl-kj1ijhk2tf55tw And want to make it in Blender
I already learned how to make radial sweep animation in this tutorial: https://www.youtube.com/watch?v=PUauJWWLqFI (very simple) and had success to make it be rectangle shape with help of this answer: https://blender.stackexchange.com/a/109005/46872
To not be completely spammer with links, below is result:
Whole procedure:

I created a plane, deleted 3 edges, left 1 edge and added screw modifier to this new object (to edge) so I can animate it like radial sweep:



I added the cube with hole in center. I set Object Properties &gt; Viewport Display &gt; Display As &gt; Wire for this cube and unchecked Visibility &gt; Renders.




I want that Plane (i.e. Edge with screw modifier) be visible only in region of cube body. I want it to be invisible as outside of cube, also in hole in center of cube.

As you can see on below screenshot, I had success only with invisibility outside of cube. Plane (i.e. Edge with screw modifier) is still visible through hole in cube center and I don't want it. Btw, material of Plane is also on below screenshot:

One more thing: I suppose there is maybe more simple way to accomplish my target - animation from linked video at the beginning of post, but as said, I'm not an expert, had no other idea and was started this way.
Please let me know if any additional info is needed and thanks in advance.
You can make parts of objects invisible using multiple tricks. Since your mesh is animated, it's probably not the easiest animating your material as well. As I get it, if you want to change the animation speed, you need to adjust the material separately. Anyways, here's how I would do it:
 
The sphere simply has a transparent shader set to blueish nothing else.
The cube is only visible if a ray has passed through a transparent shader. I guess you can also invert the sphere (animiation) and use a simple holdout shader on it, but I'm guessing that doesn't work for you for other reasons.