I have a young trans relative. They are fortunate in that they do have a partner, also trans. They are less fortunate in that their (same sex) partner is unable to work full time and they are also being to suffer health issues from the medication they take. They are both still young, the health problems can only get worse. Both are probably sterile.
Transition damages physical health. If they take puberty blockers there may be a drop in IQ. There is conflicting evidence on the risk of suicide, some that shows those who take puberty blockers have a higher suicide risk. Much of the so called "research" is actually so badly carried out that propaganda is a more accurate description. Always consider carefully who is funding it. Males who take puberty blockers will not grow a large enough penis to make a neo vagina and if they want one will need to have it made from some other body part, often the colon. That will not increase the number of people who will consider sex with them.
Transitioning a child is not something anyone should undertake - or support - lightly, yet fools do. Good advice was offered upthread on where to seek help. I'll quote it.
"I would recommend two places for support - Bayswater Support is for parents of kids who think they're trans, but won't push the narrative that they must transition on you.
https://www.bayswatersupport.org.uk/
Stella O'Malley is a psychotherapist who does some great work in this area. Look her up or contact her and see if she can put you in touch with a therapist near you who will help your son explore what is actually going on here, rather than push a trans identity on him.
Her organisation Genspect has lots of resources for parents:https://genspect.org/support/support-for-parents-and-relatives/
She co-authored a book that came out last year, "When Kids Say They're Trans: A guide for thoughtful parents" that I think you would find useful.
https://amzn.eu/d/hcw2k7I?tag=mumsnet&ascsubtag=mnforum-21 "
Try to find out who is putting these ideas into your son's head as he is being influenced. Watch Masterchef and cook with him. Show him the English football team and talk about how successful they were. Let him grow his hair but tell him no 11 year old should have hair extensions and make up at school, he can try make up at home if he wishes. Explain that life as a girl is not easier, tall about periods, childbirth, sex discrimination, male violence. Ask where he got the idea it would be easier.