> Do you think it is good policy for a country to cap its population?

That's a misconception. The goal of the initiative is to limit immigration and infrastructure strain. As a Swiss myself I can only talk about my country, and yes, it makes very much sense not to simply leave the floodgates open and allow the infrastructure to become completely overburdened, requiring constant expansion at the expense of quality of life and the natural environment. Schengen is largely a toothless tiger; the past few decades have made that clear. Germany, Austria, France, Denmark, Sweden, and Norway have all reintroduced border controls since 2015.