If your son wishes to play with barbies and wear a ballerina outfit around the house, I don't think parents should stop them. Let them do them, as they get older, they may be trans, they may not.
But to actually take the steps of medically transitioning a child is pure lunacy, and any doctor participating in this should have their license revoked.
Much like with sex, a child does not have the intellectual capacity to give consent when it comes to this issue, even if they answer in the affirmative that it's what they want.
In most cases, these are very extreme individuals with a hard left, identity politics bent who are simply imposing their ideology onto their children, which, it goes without saying, is reprehensible.