Like pretty much anything, how people go about these kinds of issues varies depending on the individual. Some people are content with just the "I think therefore I am" approach, but a lot of the others will still feel restrained by the way their body works (for example, male-at-birth children who identify as female but feel impacted by the unfeminine voice brought about by puberty), and it's not some horribly anti-LGBT taboo or something if they want to take an operation or something to give themselves that extra confirmation.