There are two method in order to set sticky single product layout.
The first way, you can apply the designed presets under Familab > Customize Preset > Single Product.
In this tab, you scroll down and see several sticky layout presets here, you only need to click Apply, the the preset will be applied for your single product page immediately.
The second approach, you can access Appearance > Customize > Shop (WooCommerce) > Single Product.
In the product layout section, you can select Sticky layout. And then, choose a Product Image Style in the Gallery section.