I agree with Pikkumyy's sentiment so I'll answer.
Take education. Unfortunately there are a lot of gender confused teenagers out there, particularly girls. There always were but its been made worse by the Internet.
To me, a "strictly sex based approach" would be what the Conservatives appear to be advocating, which is not to teach about gender and to only teach its impossible to change sex.
The problem is we know that teenagers are high risk, ego focussed due to their brain development and do all sorts of harmful things they are taught are "wrong", because the views of their peers are more important than teachers and parents e .g. drugs, underage drinking, sleeping around, piercings, tattoos, sexualised clothing etc etc.
So in my view a more effective approach would be to embed curiosity and self-determination in children, teach about gender identity and sexuality, the difference between "gender" and biology, teach about how its OK to explore different aspects of themselves and to that end allow children to dress and call themselves whatever they like without pressure, and also ban medicalised transition until people reach adult hood - probably 21. This is basically Kenneth Zuckers approach.
I think this would enable a lot of gender confused children time to grow comfortable in their bodies and probably also realise they are gay, or autistic, not trans. But it positively supports those children and their sense of self while they are going through this, as opposed to telling them their feelings are wrong which leads to self loathing and rebellion.
Some teens will still end up being trans adults but in the meantime we haven't done unnecessary psychological damage to children who aren't comfortable in their own skin.
What I'm suggesting isn't a "GC" approach though, i think that's what pikkumyy meant.