Are there any rules in place that would cause a large-sized ancestry to be inherently unbalanced?

[Salamileg]

Basically title. I know 5e has a lot of rules that mean that large races to not work, I was wondering if the same is true for PF2.

[DougSeay]

Not really. But you still have the issue of fitting. Getting centaurs up the stairs then to sneak across the roof to drop on the enemy from behind will still be difficult. And likely humorous.

[Reckless]

Reach is about the only unbalanced thing large creatures get innately in 2e.

If you consider spacing issues to be a balance to that, go for it, just realizing that it will force a resizing of many design spaces.

[beowulf99]

A large sized ancestry would also be the only character who would have to pay a premium for gear now that Small and Medium gear is standardized.

Not a huge issue since Giant Totem barbarians already have to deal with buying larger weapons, and the rules for doing so exist. But it may be a pain outfitting a lvl 1 large sized character depending on armor and weapon choice.

[Ascalaphus]

"Standing upright" large characters would have more reach, which is pretty nice, especially if you have AoOs of some kind. Could be an action advantage because enemies will need more than one Step to get away from you.

But I've seen constantly-big PCs also get a lot of punishment. A lot of the commonly used flipmats have 5ft corridors and doors. And quite often, enemies do tend to focus on the big guy, so you tend to get hit more.

[PossibleCabbage]

It's mostly a matter of being a headache in any campaign that's going to take place indoors in buildings and structures sized for medium sized humanoids, I find.