Pearl Abyss officially announced today both online and during TwitchCon that the Black Desert beta for Xbox will happen in November. Specifically from November 8th-12th, beginning at Midnight. In order to take part in the beta, you'll need to go to the website and register a profile, but the company didn't elaborate on whether or not people would be randomly selected or if everyone who signs up can play. Here's the officially description of the Xbox version from the company.
Captured in stunning 4K quality, Black Desert for Xbox One was first revealed on-stage at the Microsoft press conference at E3 2017 and will feature console-exclusive gameplay from its PC counterpart, Black Desert Online, which counts for more than 10 million players worldwide. Built from the ground-up for console, Black Desert aims to achieve the most fluid and responsive MMORPG gameplay that's possible with a controller interface.