public bool CanUpgrade {get;}

{
    //Add the style to the current project
    string stylePath = @"C:\MyStyles\OldStyle.stylx";
    //Note: Needs QueuedTask to run
    StyleHelper.AddStyle(Project.Current, stylePath);
    StyleProjectItem styleToUpgrade = Project.Current.GetItems<StyleProjectItem>().First(x => x.Path == stylePath);

    //returns true if style can be upgraded
    bool canUpgrade = styleToUpgrade.CanUpgrade;
}

{
    bool success = false;
    //Add the style to the current project
    string stylePath = @"C:\MyStyles\OldStyle.stylx";
    //Note: Needs QueuedTask to run
    StyleHelper.AddStyle(Project.Current, stylePath);
    StyleProjectItem styleToUpgrade = Project.Current.GetItems<StyleProjectItem>().First(x => x.Path == stylePath);

    //Verify that style can be upgraded
    if (styleToUpgrade.CanUpgrade)
    {
        //Note: Needs QueuedTask to run
        success = StyleHelper.UpgradeStyle(styleToUpgrade);
    }
}