Chevrolet shed some light about the Silverado EV's bed size in their press release.
The bed is 5 foot 11 long and has something Chevy calls a "Multi-Flex Midgate" which provides 9 feet of storage between the cab and the tailgate when the midgate is open.
The 40/60 second row seat has 4 configurations to maximize storage capability. With the "Multi-Flex Midgate" the Silverado EV RST can have as much as 10 feet, 10 inches of load floor and storage space.
There's a bunch of photos that show how the bed can be configured.
media.chevrolet.com
On the RST, the storage capacity of the 5-foot-11-inch bed is maximized thanks to the innovative available Multi-Flex Midgate, which provides just over 9 feet of storage between the cab and the tailgate when the Midgate is open.
A 40/60 second row seat offers four configurations that allow users to haul gear or equipment while still accommodating a passenger in the second row. With the addition of the available Multi-Flex Tailgate the Silverado EV RST enables up to 10 feet, 10 inches of load floor and storage capability. An available tonneau cover allows items such as lumber or a kayak to be loaded into a fully lockable, weatherproof storage compartment.
The bed is 5 foot 11 long and has something Chevy calls a "Multi-Flex Midgate" which provides 9 feet of storage between the cab and the tailgate when the midgate is open.
The 40/60 second row seat has 4 configurations to maximize storage capability. With the "Multi-Flex Midgate" the Silverado EV RST can have as much as 10 feet, 10 inches of load floor and storage space.
There's a bunch of photos that show how the bed can be configured.

The Pickup Reimagined: Introducing the 2024 All-Electric Chevrolet Silverado
Chevrolet Pressroom
On the RST, the storage capacity of the 5-foot-11-inch bed is maximized thanks to the innovative available Multi-Flex Midgate, which provides just over 9 feet of storage between the cab and the tailgate when the Midgate is open.
A 40/60 second row seat offers four configurations that allow users to haul gear or equipment while still accommodating a passenger in the second row. With the addition of the available Multi-Flex Tailgate the Silverado EV RST enables up to 10 feet, 10 inches of load floor and storage capability. An available tonneau cover allows items such as lumber or a kayak to be loaded into a fully lockable, weatherproof storage compartment.