not a doctor, but my experience as a trans guy has led me to believe that getting off isn't really a function of hormones so much as it is nerves. hormones help arrange some things (e.g. vaginal lubrication) that can make getting off easier / more enjoyable, but with enough patience, time, and comfort, you can more or less get off with the same intensity post-transition as one did pre-transition
although transmasc hrt does open up some new ways to get off that your kid will probably enjoy a lot lol