I don't see a set with the code SOS in the Standard meta changes. Could you clarify what you mean by SOS? Here are the currently legal Standard sets for reference:
- EOE – Edge of Eternities
- FIN – Final Fantasy
- TDM – Tarkir: Dragonstorm
- AER – Aetherdrift
- DSK – Duskmourn: House of Horror
- BLB – Bloomburrow
- OTJ – Outlaws of Thunder Junction
- MKM – Murders at Karlov Manor
- LCI – The Lost Caverns of Ixalan
- WOE – Wilds of Eldraine
Did you perhaps mean one of these sets, or a different abbreviation? 😊