honestly it's a surprisingly niche combo in mainstream literature. If you're open to related reads, start with a few classics: 'Orlando' by
virginia woolf gives you a graceful, almost magical gender change across centuries (no hypnosis or brainwashing, but it handles identity in a way that feels like an external force reshaping a person). 'Middlesex' by Jeffrey Eugenides and 'The Left Hand of Darkness' by Ursula K. Le Guin explore gender and fluidity without any coercive mental control — they're more sociological and psychological than hypnotic.
If you want actual coercion or enforced personality changes, look adjacent: 'The
stepford wives' by Ira Levin is a creepy meditation on engineered conformity and control (not gender-swapping, but women are basically turned into different people by external means). For the exact pairing of hypnotic mind control causing gender transformation, that trope is far more common in self-published erotica, fanfiction, and niche web-serials than in mainstream novels. People write whole series on sites devoted to transformation and hypno-fiction.
So my practical takeaway is: for literary depth about gender, read the classics I mentioned; for the specific mind-control + gender-bend kink, dive into niche online communities and search tags like 'hypnosis + transformation' — you'll find plenty, but be ready for mature content and uneven writing. I find the contrast between literary nuance and pulpy fetish fiction fascinating, honestly.