Hi @Mehmed ,
Thanks for your post.
Here are 2 threads related to your inquiry.
The first describes at a high level how Cesium picks optimal zoom level zoom level depends on viewport size?
And the second explains methods to modify this when using the library
Fixed Zoom Level for Different Screen Widths
I hope these are useful for your question. If not, happy to try to provider more explanation or resources.
Thanks,
Luke