Of course a periscope zoom takes up more internal space. Instead of having the lens on top of the sensor, it's next to it with the zoom optics between them.
This is the Ultra 22 camera array, want to guess which of the four is the Periscope zoom.
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Here are the Xperias you mentioned, guess which camera is the periscope zoom.
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Here is the P30, you can see that its 5X periscope zoom takes up more internal space than the other cameras.
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The Pixel 6 Pro's zoom is almost the same size as the two separate cameras.
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Now all that being said, it really depends on what the other cameras are. If thew 15PM has the zoom and two cameras, that array may not take up more space that the 15P's four cameras.