The three rear cameras get by with just two connectors—the main camera and the monochrome camera share one port, while the telephoto camera gets the other all to itself.

From the side we can compare the relative elevations:

Left: 20 MP (monochrome ƒ/1.6). Middle: 40 MP (main camera ƒ/1.8). Right: 8 MP (telephoto ƒ/2.4)

Lastly, we've got all four eyes lined up for inspection, including the P20 Pro's selfie cam with only 24 MP.