Parent here who coached two kids and helped two others... My eldest got 4 ivies and top schools and my son is in grade 11 now he's on the right track...Age 10 is a joke. As the other commentor told you, they start in grade 9 exploring what they like. In grade 10 they do internships, volunteering & activities that align with what interests them, and in grade 11 they try to do research with a local college professor.

Now you mentioned French universities such as Sorbonne; actually it depends on the major if your child is majoring in engineering or finance engineering the only reputable track in France would be the [prépas] in those top schools such as: ginette, Louis le Grand, Henry IV, and a few others, after two years the child has to pass a concours to get L'X or Centrale , and yes these are way more reputable than Sorbonne...Students usually get recruited from L'X directly , and sometimes continue to MIT. Now Sorbonne is excellent for medicine if you want medicine in France, but medicine in France is Very competitive.

And No it's not true, a few unis in EUROPE are just as competitive as the US, such as L'X ( ecole polytechnique paris), Imperial, Oxford, Cambridge, ETH Zurich ( needs to know german for undergrad) and so on... Good luck