Hello @Damien,
To create new product pages, please navigate to XStore > Theme options > Woocommerce (Shop) > Single product builder. For a better reference, please see the attached image: https://postimg.cc/hJNm4hLg
The Custom Layout Single Product Builder applied on all the products globally on your site and you can use/create multiple layouts and assign them to different products using Multiple Templates as per your requirements.
You must turn on the Single Product Builder under XStore > Theme Options > Woocommerce (Shop) > Single Product Builder > Layout and set/build the layout according to your requirements. Please refer to the image provided here: https://ibb.co/gPnmbV3 , this will apply globally on all the products on your site.
For applying that template to an individual product or category, please click on “Multiple Templates” and create or assign the condition to apply that template to the particular category or product: https://postimg.cc/47S2rsv9
Like this: https://ibb.co/D9ysV8f you can apply that template to the particular category of the product and then all the products of that particular category will work on the same layout
Kind Regards,
8Themes Team.