Active site feature

public void Main(string[] args)
{
    var siteCollectionUrl = "http://your_site_url";
    var featureId = "379c069c-c650-451c-8887-aaaf91bf5df8";
 
    using (var ctx = new ClientContext(siteCollectionUrl))
    {
        var web = ctx.Web;
        // activate feature
        ctx.Load(web);
        ctx.Load(web.Features);
        ctx.ExecuteQuery();
        web.Features.Add(new Guid(featureId), false, FeatureDefinitionScope.Site); ;
        ctx.ExecuteQuery();
    }
}