According to
the Mayo Clinic: "Effects of hormone therapy for transgender people are reversible if you stop taking the medication, but the degree to which they can be reversed depends on how long you've been taking it. For example, the effects of estrogen, such as skin softening, muscle tone reduction, and fat redistribution, are reversible. However, other effects, such as clitoral growth, facial hair growth, voice changes, and male-pattern baldness, are not reversible.
Puberty blockers, such as GnRH analogues, are also reversible and can be stopped at any time. If you stop taking puberty blockers and haven't started hormone therapy, your body will go back to the puberty that had already started. The World Professional Association for Transgender Health (WPATH) considers puberty blockers to be a "fully reversible intervention."