Actually, that's very simple :
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In the French Republic schools (primary and secondary) : no signs of religion (cross, veil, kipa etc, etc) = laicité (the State is neutral and accept all religions in private).
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In the French Catholic schools (which are funded by the French State and whose teachers are paid by the French state) : you can wear what you want (cross, veil, kipa etc etc).
Every town, every city has at least one French Republique school (
école publique) AND one Catholic school (
école privée).
It's been that way since 1905 (State-Church Separation Law).
In some big cities, there are Jewish schools and now, some Muslim schools too (not a lot).
Please, don't ask for Protestant schools as the Protestants are a minority in France and go to the Catholic schools or the French Republic schools (where all religions are welcome but not practised).