Let’s say I have a 9th Generation kindred that embraces someone today. They’d be a fledgling, but of 10th generation. Is there a way to manually adjust that and what that would do for blood potency? I can type in the Generation, but the blood potency and all that comes with it doesn’t change.
Hello Niah!
As the current rules support creating characters of 11th generation or later, there’s no ‘one-stop’ to make this adjustment, however you absolutely can use the toolset to make this happen at your table, just as you could on paper.
While on the sheet, you can click or tap on Blood Potency to open it’s drawer. There, you could choose to either spend XP (of which you can grant the character an amount equal to what you think they should be granted to match their power at the 10th generation vampire, or just the amount needed to increase Blood Potency, which is shown there in the drawer) or override it, by clicking on the 
icon on the top right of the drawer. In there, you can enter whatever rank you want for blood potency.
The drawer method applies to other aspects you’d like to change outside of the standard player character rules! You can use it to adjust humanity or skills/attributes as well.
Finally, any additional powers can similarly either be added by granting additional XP and purchasing them, or by adding them directly to the sheet by clicking ‘Manage’ above the powers/disciplines section. In that drawer you can either purchase with XP, or use the slider to turn XP off to add freely.
Hope that helps in making the 9th generation vamp of your dreams!