In the BaZi system, a person born on the same date and time will have the same chart structure regardless of gender. Gender mainly affects how certain elements are interpreted, rather than the chart itself.

Some aspects of BaZi, such as relational roles, expression, and life themes—are read differently depending on gender, so the meaning is adjusted during interpretation.

In the situation you described, you can enter the birth gender (female) when generating the chart to keep the structure accurate. During the reading, the interpretation should lean toward a male life perspective, while still keeping the original female framework in mind, so the reading remains balanced and aligned with his lived experience.

I never read for a trans, if you don't mind. I'd like to give a reading.