I'm not associated--in any way--with the B-21 bomber. But, I do know a bit about America's current aircraft technology.
The B-21 is probably fast, not just supersonic but hypersonic.
The B-21 can probably drop, shoot, (or materilize?) all current bomb weapons including anti-matter bombs.
The B-21 will probably have electonic 'Radar Invisibility' in addition to radar absorbing materials.
The B-21 will probably have Directed Energy Weapons (Lasers), both defensive and offensive.
The B-21 will probably be able to fly combat missions without a pilot!
The B-21 will probably fly so high it will be mistaken for a UFO!
And, the B-21 probably could be given 'Warp Technology'--and suddenly appear over target!
[Will they sneak off, mate and create new B-21's?]