If you’ve had gender reassignment surgery that includes the removal of your ovaries (oophorectomy), your body can no longer produce significant amounts of estrogen. In this situation, estrogen blocker medication is not necessary, because the surgery itself provides definitive and permanent suppression of estrogen production.
Other kinds of gender-affirming surgery don't affect estrogen production. If you can afford it, then GnRHA blockers are great at suppressing the ovaries and stopping them from producing oestrogen. If funds are limited then after some time testosterone is often enough to suppress the ovaries, stop periods and reduce oestrogen production.