When an image is clicked, it will expand to the full size of the gallery.
More information
https://www.wysiwygwebbuilder.com/nineimagesgallery.html
You can also download the new extension via the Extension Manager: Menu->Tools->Extension Manager->Online Gallery->Galleries
This extension is from my private collection. It is provided "AS IS".
Please read the included documentation for help.
https://www.buymeacoffee.com/wysiwygwb