This is exactly why the fight for truth and reality has to continue.
While we have a world where messages bombard children with lies that they can be anything they want to be (whether that is influencer / celebrity / the opposite sex); then a child has no real reference to reality.
While we have schools and organisations telling children lies that they can become the opposite sex - rather than teaching them the truth of biological reality, that you will always remain your natal sex and teaching them how to navigate puberty / adolescence and all the confusion that comes with that; then children have no idea of the natural boundaries
While we have governments of politicians that believe that a man can become a woman or that some women have a penis, then the lies start high and wide and appear to become the truth - how does a child know to not believe the lies being told by those in charge?
While we have sexism and narrowly defined gender perceptions in society - that girls and boys play with different toys / that pink is a girly colour / that certain jobs are for men and others for women; then how do children know how to express themselves as the more sensitive boy / more 'robust' girl whose interests are not easily pigeonholed into their sex / gender by society?
While we have an oppressive society that puts men first and women well below, how does a girl grow up and not want to become a man with all the apparent advantages - seeing a sex change as a way out of oppression?
While we have toxic masculinity that believes that men can ride roughshod over women - how does a boy learn to see transwomen as men so often playing out fantasies about being in women's spaces and realise that is wrong?
While we have social media that is allowed to rip through society telling any lies it wishes without anyone doing anything about it, and when children are exposed to it without the strength to handle it or fight back, how is a child meant to stand up and be different? If they are told to change sex to conform, how do they know that is a lie and wrong?
While we see organisations as 'grown-up' as banks and NHS and unions publicly declaring that they are going to disobey the law and that the Supreme Court judgment is wrong - how do our children learn to discern or judge or trust who is right?
While we allow our children to grow up in a society that is increasingly disintegrating, where social media, peers and unregulated organisations influence more than parents and local community who know the child - how is a child to discern truth from lie and know how to navigate their teenage years?
We need a return to truth - as has been referenced for years this is the Emperor's New Clothes - society knows that sex is immutable and that you can not transition from one to the other - yet weakness and power plays allows the myth to continue - and damage our children.
Until we return to the truth, it will be almost impossible for parents to provide enough counter-balance. There are great parenting comments above - especially the approach of confirming choice and identity and lifestyle (e.g. play / jobs / dress / etc.) while also confirming the biological truth that you can't change sex. Not - you can become a girl, but you can be the boy you want to be - not you can become a boy, but you can be any girl you wish... But even with these, the weight of deception and deceit in society is so huge it becomes a losing battle for parents.
There is no doubt, this will become the nation's biggest safeguarding scandal of all time - when we look back in 20 years we will be horrified at the lives damaged and lost by society perpetuating lies and taking children by the hand and starting hopeless journeys to the impossible, with all the physical and mental damage that entails.
It is understandable that some parents will object to the OPs comments - they will feel personally attacked and understandably, (despite there being no personal attack against them), but that doesn't mean that we should be quiet about the needs - sadly those who are already casualties will never fully heal, but we can fight to avoid new casualties.
And it starts with truth. The momentous fact about the April SC judgment at its most basic is that it unequivocally confirms that this is a black and white matter - you are boy or girl / man or woman and that can not change. That one fundamental fact re-established and put centre-stage means that we can start to re-build an honest society from there. Whatever the lies and deceitful arguments that will be put forward with re-doubled energy by those whose credibility relies on the lies being believed - we can now always return to the basic biological and factual reality which can not be denied. From that point we can start to rebuild guidance / advice / help / support etc. so that our children as they enter their teenage years, with puberty changing their hormones, with wider circles of influence challenging them - can have a grounded certainty in who they are biologically - giving them far more freedom to express themselves how they wish...
...they can be any shape of boy or girl they choose - they just can't change sex.