Game Pass EA Play subs (whether separate sub or through GP Ultimate) will get access to the game, (and to the currently running Open Beta, that’s how many are trying the game at the moment) but with the standard EA Play limitations: Early access, initially only a limit of 10 hours of play time, access to Standard Edition only once the game gets formally added to the EA Play List Library (normally about 6 months after game release). Pretty much the same conditions for all EA Play subscribers, whether you subscribe through Game Pass, Steam, or directly through Origin.
Here’s a comparison between the two EA Play versus EA Play Pro for Battlefield 2042:
Basically, if you want full access and all the bells and whistles you’ll need to buy the game outright, or opt for EA PlayPro.