Nulumia themes no not use any form of plugins for features, rather all features are built into the theme itself. Thus, all feature settings are located within the Style Properties section of your theme.
Visit your Xenforo admin page and click on Appearance -> Styles. On the next page, select 'Style Properties' for your theme.
You will notice many new property groups have been added:
Each of these property groups contain all the settings you need to customize your theme, along with full custom Style Properties to color and style your theme features! In the next section, we'll walk through each of these property groups in order, with instructions on how to edit various settings.