Whether you use the theme's specialty templates (e.g. Image Scrolling) or a custom duplicate of the Default product, you can assign the template to multiple products through the Products admin.
Bulk-assign products to templates
- Open Products in your Shopify admin
- Use the checkboxes beside each product to select the products for the template
- Select Edit products
- In the Bulk editor, select Add fields then Template
- Use the new column for Template to adjust each product
- Once all the products have the template adjusted, click Save