Quebec has established the language planning it decided on. It did so long time ago. I think the Charter of the French Language was the second bill the Parti québécois government passed, in 1976 or 1977. It did so precisely to reinforce the French fact in many sectors, education in particular. Everyone in Quebec was supposed to go to French-language schools. Some exceptions were made for people who had attended primary school in English and who could thus send their children to anglophone schools. Otherwise, however, everyone, including newcomers, had to go to a French-language school. That was the measure that did the most to preserve French.
On April 29th, 2021. See this statement in context.