Large sized natural weapons?

[SangoProduction]

Do natural weapons scale up in damage when you increase your size?

[CharonsHelper]

Yes they do.

[Darrin]

Do natural weapons scale up in damage when you increase your size?

Yes. Look up Improved Natural Attack in the Monster Manual (pg. 304). Changing size progresses the damage up or down according to the pattern listed there.

[SangoProduction]

OK cool. Does this also apply to abilities/spells that grant natural attacks, like the Totemist soulmelds?

[Necroticplague]

OK cool. Does this also apply to abilities/spells that grant natural attacks, like the Totemist soulmelds?

It depends on the exact wording of the ability or spell. Most things like that will list the damage for a Medium creature (and thus, to find damage at other sizes, you'd refer to INA's table).

[Darrin]

OK cool. Does this also apply to abilities/spells that grant natural attacks, like the Totemist soulmelds?

That's... not entirely clear. The natural attacks granted by soulmelds aren't always given a lot of detailed information. The text may not state directly that they change by size, can be used as secondary attacks, etc. So RAW (Rules As Written) may be iffy, and you may have to go by exactly what the text says. RAI (Rules As Intended/Interpreted) generally says yes, they are adjusted by size like any other natural weapon.