The iPhone 12 spec report just went up with @EveryApplePro. Here are some of the highlights:
120hz iPhone 12 Pro series IS being tested. Display calibration is hard and unless Apple can perfect it, they won't do it. They won't do 90hz, 120hz nothing.

Apple is working on dynamically switching between 120hz and 60hz depending on what you are doing/have open. 120hz is a huge battery drain, so it's needed.

The battery will need to get larger because of this. 120hz, is again, a huge battery drain. For battery to even be acceptable, Apple needs physically larger batteries. Optimization can only do so much.

Navy Blue is coming and is being tested in a few different shades. It will have the same frosted back glass.

The flat sides of the phone are stronger than the previous angled ones.

The Face ID module is being shrunk. It will be moved around to fit everything. Apple will also be working increasing the angles it works at and using a new "dynamic zoning algorithm" for faster speeds.

The cameras are getting improved. They are getting larger pixel sizes with lower MP sensors. They tested 64MP, but it wasn't good enough to make it to launch. They want full sensor auto focus using dual pixel AF before they go to higher MP counts.

LiDAR is going to be there and it's going to help with auto focus speeds in low light, as a normal sensor can't do it well. Subject detection in extreme low light will improve as well. EIS in Night Mode is going to be improved to help hand-held night mode pictures.

Slow-mo is gonna get better. Better low light video but the source didn't mention higher FPS options. The better low light is part software, part pixel size.

Night mode is being improved for longer exposer night mode pics. Could greatly help astrophotography.

White balance is also getting improved. It's much better, which is a good thing as it did get worse in later iOS 13 builds.

LiDAR will be used for portrait mode as well. The hardware is also there for portrait video but it won't be included at first. It could be delayed to iPhone 13 or later iOS 14 update. Could be beyond that as well.

Audio Zoom is also getting more precise with better beam forming microphones. It got better on iPad Pro, MacBook Pro, and now iPhone.

Next gen SmartHDR is getting improved and will be on all 4 iPhone 12 models. It will have better noise reduction in semi low light.

Night mode is being extended to the telephoto camera. That telephoto is also being tested with 3x optical zoom. They are trying for 25x to 30x digital zoom, but it depends on how good it can be.

Ultra wide FOV won't change and won't have night mode. Ultra wide cameras get less light due to the nature of ultra wide lenses.

iPhone 12 prototyping will end soon. Late May, actually. Should get more accurate CADs and leaks starting in June.

As for WWDC, AirPods Studio headphones should be releasing for about $250, as @jon_prosser had said. Craig is also working on more demo videos for iOS/iPad OS 14.

Correction: $349