Yes, I am aware of the WPATH Standards of Care. However, both cross sex hormones and surgical interventions are happening with minors, even among WPATH affiliated surgeons.
Here are the applicable guidelines for those interested:
https://www.wpath.org/media/cms/Documents/SOC v7/SOC V7_English2012.pdf?_t=1613669341
Irreversible Interventions
Genital surgery should not be carried out until (i)patients reach the legal age of majority to give consent for medical procedures in a given country, and (ii)patients have lived continuously for at least 12 months in the gender role that is congruent with their gender identity. The age threshold should be seen as a minimum criterion and not an indication in and of itself for active intervention.
Yet a number of surgeons have performed such surgery, on patients as young as 15, even WPATH associated surgeons.
This article is a survey of attitudes of 20 WPATH affiliated surgeons in the US. 11 of the 20 performed genital surgeries. The article surveys methods, attitudes, also discusses the lack of teeth to any standards of care guidelines, as well as varying views by the doctors as to appropriateness of various techniques.
Some quotes.
https://www.transgendercounseling.com/temp/wp-content/uploads/2018/09/Milrod-Karasic-2017-FINAL.pdf
But, despite the minimum age of 18 years defining eligibility to undergo this irreversible procedure, anecdotal reports have shown that vaginoplasties are being performed on minors by surgeons in the United States, thereby contravening the World Professional Association for Trans-gender Health (WPATH) standards of care (SOC).
Conversely, female-affirmed teenagers must defer orchiectomy and/or vaginoplasty until 18 years of age to stay compliant with the SOC and the legal age of majority in the United States. This position also is supported by the Endocrine Society, a worldwide organization dedicated to the education and practice advancement of endocrinology. The society has issued recommendations concerning the treatment of trans youth, in which it is suggested that genital surgery be deferred until the individual has reached 18 years of age
Contrary to the concise criteria guiding decisions for post adolescent surgical treatment [p. 54], there are no guidelines in the WPATH SOC that support the surgeon in the decision to perform vaginoplasty on transgender women younger than 18 years. The surgeon must rely on evaluations by other professionals, careful patient selection, and the personal conviction that proceeding with surgery is the right decision, with the added legal burden of obtaining consent from parents in lieu of the minor and assuming principal responsibility for the physical risk to the young patient who might not always be compliant with or fully understand post-operative care. The surgeons who perform the procedure on transgender minors have, without exception, refrained from publishing any peer-reviewed outcome data or technical articles on this small but increasingly important population
Nine surgeons had never performed vaginoplasty on a transgender female minor, and the remaining 11 participants reported 1 to 20 cases per surgeon. Of the 11 surgeons who had performed vaginoplasty on a transgender female minor, 10 were in private practice. Reported ages of minors undergoing surgery ranged from 15 to “a day before 18” years (surgeon 7). Most participants had noticed a definite increase in the number of minors requesting information about the procedure on their own or being referred for vaginoplasty by their mental health providers.
However, despite the desire for the WPATH to create mechanisms for data tracking and providing greater oversight, a plurality of participants perceived the SOC as purposely“vague”and more as“inherently flexible guidelines”when the question of lowering or keeping the minimum age requirement was brought to the forefront. In fact, approximately one third of participants agreed that the SOC were appropriate in maintaining 18 years as the minimum age criterion for vaginoplasty; the remaining surgeons favored a case-by-case approach or endorsed a shift toward accepting patients younger than 18, although none were certain when any such changes would officially occur.
Paradoxical attitudes to the WPATH and its standards are not unique to this particular group of affiliated members; a study including 36 psychologists, psychiatrists, and endocrinologists in 10 countries showed that the WPATH SOC were considered “too liberal and too conservative."