Welcome to our board, Thisisnotelizabethbush
! Do you remember (or have some idea) where (which publication) these sketches are published in? We have bits & pieces of various sketches of FMA characters by Arakawa-sensei
posted in our FMA manga forum
as they get published in various books (FMA Chronicle, Perfect Guidebook, FMA Rough Sketch Gallery, etc.) like this
, although I don't know which specific sketch you're looking for and hence I can't guide you to any specific thread...