Tiny creatures cover from larger creatures

[SuperParkourio]

Tiny PCs are stated in the rules to not gain automatic lesser cover from being in a larger creature's space, just like other Tiny creatures. But I can't find this general rule for Tiny creatures. Where is it?

[Finoan]

I don't think it is stated outright. It is a result of the rules for cover and soft cover.

The line of effect has to pass through an obstacle in order for cover to be granted. If a tiny creature is in the same space as a different creature, then the line of effect doesn't pass through the obstructed space - it only passes into the space.

The game rules don't have sub-locations in a space for tiny creatures, so since both creatures are in all locations of the space, the game rules make no distinction of which creature a line of effect will contact first.

You can narrate your tiny creature being on the opposite side of the enemy whose space it is sharing, but that has no mechanical effect. The creature doesn't provide cover because your tiny creature is also mechanically on the near side of the larger creature and has no cover.

[NorrKnekten]

Its found in the ancestry guide which is to my knowledge the first instance of playable Flying/Tiny ancestries, underneath the Special Rules

"Ancestry Guide p.66" Tiny PCs wrote:

PCs are typically Small or Medium size, but some ancestries, such as most sprites, are Tiny instead! Being Tiny comes with its own set of rules about space and reach. A Tiny PC can enter another creature's space, which is important because their melee Strikes typically have no reach, meaning the PC must enter a creature's space to attack it. Like other Tiny creatures, the PC doesn't automatically receive lesser cover from being in a larger creature's space, but circumstances might allow them to Take Cover in this instance. They can purchase weapons, armor, and other items for their size with the same statistics as normal gear, except that melee weapons have a reach of 0 for them (or a reach 5 feet shorter than normal if they have the reach trait). Remember to adjust the Bulk of items and the PC's Bulk limit for Tiny size (See Items and Sizes).

While I understand this essentially just repeats the same thing Howl of the Wild links, it's probably more pointing to the fact that just like how Tiny creatures cannot flank Rules as written, a line cannot be drawn completely trough another creatures space if the creature is sharing a space with them. Flanking Rules