The mildest, lowest-consequence form of care would be
social transitioning such as use of preferred pronouns, freedom to have toys/clothes/etc. of their choice without stigma and so on. For kids with gender dysphoria whether severe/diagnosed or not, that would of course be a treatment process which should be respected, much like accessibility tools for disabled people, gifted/remedial/vocational programs for kids of differing aptitudes and so on. But it seems that many conservatives would oppose (and teach their kids to oppose) even that mildest form of gender affirmation. By all appearances, conservatives are determined to ensure that transgender folk
need medical/surgical treatment to have even the faintest hope of having their preferred gender recognized.
Given that social climate, the recommended first stage of medical treatment for children, if required, is use of puberty blockers to prevent development of the unwanted/wrong secondary sex characteristics and minimize complications with a full surgical transition if desired once they reach adulthood.
Hormones? Surgery?
At what age? Sixteen? Ten? Five??
Social transitioning can begin at more or less any age. Diagnosis of gender dysphoria requires the presence of multiple key diagnostic criteria over a period of at least six months IIRC, which would be a sensible guideline for any parents; children should have the primary say in how they want to be treated, subject to health and legal requirements obviously, but there's also the important distinction between short-term whimsy and an actual disconnect between sex and gender. The first stage of medical intervention - puberty blockers - are not administered until after the onset of puberty, potentially after years of recognized dysphoria and social transitioning.
Holey Hannah, I've raised three kids and the idea of letting them decide to get permanent, life-changing "treatment" as a minor is not such a hot idea, imho. Considering the degree to which post-surgical trans report continued dissatisfaction and depression, or regret... letting minors with their scientifically-proven-undeveloped brains make this choice, against parental judgement, strikes me as a very bad idea.
How valid do you imagine "parental judgement" would be in diagnosing sickle cell anaemia or AIDS or any of a thousand other conditions, even before introducing the widespread prejudices and even greater scope of ignorance and misinformation surrounding trangenderism? Ideally of course parents should be in the loop and on board with their children's needs. But allowing parents to block medical treatment of teenagers' persistent self-reported experience and needs, based on the parents' prejudices and ignorance, seems like a wildly misguided notion.
There's potential downsides both to growing up as the wrong gender and to blocking/delaying puberty with a view to potential later transitioning: The
only person who can reasonably make the choice which of those risks to take is the teenager themself, obviously with appropriate information from medical professional/s.