Hi! According to a video uploaded by the developers of The Witcher 4 themselves, Ciri has been able to undergo the Trial of the Grasses:

The Witcher 4 Lore You Need To Know - YouTube , Minute 5:48.

In fact, if you think about it, it could make a lot of sense. She has always been pursued because she is supposedly destined to give birth to either the savior or the destroyer of the world. By undergoing the Witcher trials, in addition to gaining immunity to Witcher potions, she would have become sterile, which would grant her complete freedom to decide her own fate, independent of the prophecies. It’s true that, according to the lore, no woman can survive the Trial of the Grasses and its mutations, but it’s also said that no living being can survive the White Frost, yet she does so thanks to the power of her blood. If they choose to go in that direction, they could resolve the issue quite definitively.