If she has, then she didn't go too big. Reminding me a bit of Kate Hudson and the brief controversy there was when she was suspected of augmenting herself.
Ironically, while her role in the Substance likely was a motivating factor in getting a boob job, she clearly didn't go that big. But I'd say, until we see her topless again, we won't absolutely know for sure, given many instances of her being "bigger" could be chalked up to bras, that time of the month, extra weight, etc.
In either case, she likes to show off her body entirely too much for this to be the end. And if she got a boob job, she will definitely want to show them off down the line.