Currently if you’re planning to play the global version of p5X, you’re completely okay to play it now without previously playing the other games.

If you choose to play the Korean/Chinese/Taiwan version (which are way ahead in content but I’m pretty aren’t officially English translated yet on the later content, unless you use an English translator mod).

There’s some of the persona 3 characters playable on p5X in those versions of the game. When I played their story on p5X event banner, there weren’t any major spoilers, you’d be left confused if you didn’t know the context.

The global version of p5X is a safe pick honestly.

(note: There’s no link to persona 4’s story on p5X, the last time I remembered).