They will make the heavy-lift, fully reusable two-stage rocket called the Terran R. Their first rocket is the Terran 1 and it is scheduled for a first orbital flight at the end of 2021.

The new rocket, Terran R, will be just a bit smaller than the SpaceX Falcon 9. Terran R is 216 feet tall while the Falcon 9 is 230 feet tall. Terran R will have a 20000 pound max payload while Falcon 9 has 22500 pounds of max payload.

Terran R will be 3D printed and built in 60 days.

Relativity Space wants to have the following advantages:
Reliability: 100x Fewer Parts
Speed: 10x Faster Production Time
Flexibility: No Fixed Tooling and a Simple Supply Chain
Optimization: Compounding Iteration Quality and Time Improvements