pf2e.fyi
From Pathfinder Lost Omens Impossible Lands, which isn't enabled.

Flexible Form

FEAT 1
Prerequisites any heritage except strong oak

Your body is as supple as a sapling, capable of bending without breaking. You become trained in Acrobatics, and if you roll a success to Squeeze, you get a critical success instead. If you would automatically become trained in Acrobatics (from your background or class, for example), you instead become trained in a skill of your choice.

Pathfinder Lost Omens Impossible LandsOGL