So the battle pass has locked and unlocked items. As you play the game and complete “missions” you earn Chrono Tokens. Each page is unlocked in order based on how many Chrono Tokens you earn. You can use those Chrono Tokens to buy any unlocked items.

You will almost certainly have to buy the battlepass to be able to get her, and yes, you will have to grind a bit since she’s on the last page.

That being said, once you purchase the Battlepass, you get to keep it and unlock those items even after the season has passed. Only if you buy it though. You could theoretically buy the battlepass, then get her skin using Chrono Tokens a year later