Can a large or bigger monster use Alter Self to shrink down to medium?

[Quintus E Deveron]

Or is there something in the polymorph rules that would prevent a large or bigger dragon using alter Self to appear as a human, elf or etc?

[TxSam88]

that seems to be legal..

https://paizo.com/threads/rzs2rkxy?How-does-Alter-Self-really-work

[Melkiador]

It's a handy trick to use to let larger companions, like huge eidolons, navigate a dungeon. They can stay in a humanoid form until a combat starts, and then you only have to spend a standard action to dismiss the spell and bring them to full size.

[Azothath]

Alter Self on AoN.
Works as advertised. As Mstr Yoga says, "size matters not"...