How should I comfort my mom?

My mom is supportive of me being trans (she’s the greatest mom to have ever lived, I will die on this hill), but among being scared of how people (especially extended family) will treat me for being trans (as well as wanting to warn me about misogyny), she’s also scared that I may start HRT only to realize it’s not what I want and end up stuck with the permanent side effects of it. What could I say or do to make her less scared of this?