s'ouvrir and ouvrir

Bonjour Jean ! That's an interesting question ! We will use "s'ouvrir" when meaning "to open *on* oneself", referring to a physical action: "La porte s'ouvre." "La pièce s'ouvre sur un décor splendide." (The play opens on a splendid set.) -> Here it's probably a usage referring to the opening of the curtains at the beginning of a play. when meaning "to open oneself [emotionally]" "Je m'ouvre enfin aux autres." or in context with parts of the body: "Je me suis ouvert le genou." (I cut my knee open.) I hope that's helpful! Bonne journée !