Hi Alex,

If you want to change the tab order for particular page then you can use this-

[GroupDefinitions]
public static class TabNames
{
    [Display(Order = 100)]
    public const string Sidebar = "Sidebar";

    [Display(Order = 110)]
    public const string Description = "Description";
}

For more information you can refer below article- 

https://marisks.net/2016/01/30/episerver-custom-tab-ordering/

Thanks

Ravindra

And for the custom tab ordering per page type you can then use (using the link above to support the new CustomTab attribute)

[ContentType(GUID = "a35c0203-e548-4918-b932-05205cc8c491", Order = 1)]
[CustomTab("Sidebar", 100)]
[CustomTab("Description", 110)]
public class StandardPage : EditorialPageBase
{
    [Display(Name = "Text", Order = 10, GroupName = "Description")]
    public virtual string Text { get; set; }

    [Display(Name = "Sidebar", Order = 10, GroupName = "Sidebar")]
    public virtual ContentArea SidebarContentArea { get; set; }
}