Soprano Brenda Harris has sung all three Donizetti queens: the title roles in “Maria Stuarda” and “Anna Bolena” and Elizabeth in “Roberto Devereux,” a recounting of her love affair with Essex. The tragic outcomes these women in power experienced or precipitated were choreographed by those around them. On Sunday she becomes the source of that power when, as Elisabetta, she orders the execution of her cousin. Washington Concert Opera’s production of “Maria Stuarda” also features Georgia Jarman in the title role, Patrick Carfizzi as Talbot, Troy Cook as Cecil and Michael Spyres as Leicester.