@{
    var htmlTemplatesJson = JsonSerializer.Serialize(new[]
    {
        new { name = "Announcement", html = "<h2>Announcement</h2>..." },
        new { name = "Meeting Notes", html = "<h2>Meeting Notes</h2>..." }
    });
}

<richtextbox
    name="basicTemplatesEditor"
    toolbar="full"
    height="400px"
    html-templates-json="@htmlTemplatesJson" />