The Copy+Paste Styles feature is a great time-saver. It allows you to copy the styles of a block, and paste them into another block of the same type.
For example, if we have three Container blocks with a black background and white text, but we change it to a white background with black text, we can use the Copy+Paste Styles feature to copy the new styles and seamlessly apply them to the other two blocks with only a couple of clicks.
The feature only works for the block you currently have selected. If you select a Container block, it will copy+paste the styles for that Container block into other Container blocks. It does not affect any blocks inside the selected Container.