"What is your opinion of children transitioning genders?"
First, nobody, not even trans people, "change gender". Trans people transition to affirm their inborn gender identity, not change it.
Next, children under 12 may socially transition (name change, dressing and grooming), but nothing medical is done until they are at least 12.
At 12 puberty blocking GnRH inhibitors may be started, but they don't cause any physical change, they only prevent puberty from proceeding.
Also studies show that if a child is still insistent on their gender at age 12 there are almost certainly trans and will not "change their mind". The Dutch gender program has been treating young trans teens for 30 years and as far as I know no child who started medical treatment "changed their mind".
But, even if they did, no harm would have been done since hormones at not prescribed until at least 14 and usually 16.
So as you can see the entire process for evaluating and treating trans kids is extensive and well thought out and backed up by research. Because it is I support the process.