In three historical anthologies — The White Queen, The White Princess, and now The Spanish Princess — Starz has explored the lives of overlooked women in positions of power. The series has only gotten stronger with each new installment, linking together an important lineage of women who created their own agency within the constructs and traditions of the English throne, and changed history because of it. The series, each based on a variety of books written by Philippa Gregory, has also increasingly included outside materials to help contextualize the era and these fascinating women. Some liberties are taken for dramatic purposes, but …