I'm pretty sure that's a sidequest in Starfield. The ECS Constant colony ship set off in 2140 to colonise a planet, arriving in 2330 at the planet Paradiso, which had become a luxury resort planet for the rich, because shortly after the ship left, humanity invented the grav drive and every ship just zoomed right past them.

Any civilization capable of sending missiles across the galaxy should be more than capable of simply sending a tight beam of gamma radiation to sterilize the planet. No need for earth shattering explosions. Just a flood of radiation engulfing the planet for a minute or two and everything not buried a mile underground will be dead. There would be no warning either.

And that's if they don't bother to just blow up the sun.