https://www.cnet.com/news/pixel-4-4-xl-rumors-price-specs-leaks-features-everything-else/

While previous Pixel XLs launched with just a single camera on the back, but according to leaked photos posted on SlashLeaks, the Pixel 4 XL will have two rear cameras. Google has typically relied on its camera software, to do things (like portrait mode) other cameras use multiple cameras to accomplish. 

The same leaked photos also indicate that the yet-to-be announced phone will have a hole-punch display solution for its two selfie cameras, similar to the Galaxy S10 Plus.