To make the new form fields appear on product pages, you need to set your customizable products to use the newproduct-customizable-template.liquidtemplate that you created.
I want to add a new variant to my shop. I got notes on how to do it. When I get the this part, I can't find Theme templates. Please helpApply your new template to a product
To apply a template to a product:
From your Shopify admin, go toProducts>All products.
Click the name of the product that will use your new template.
In theTheme templatessection, chooseproduct.customizablefrom theProduct templatemenu.
The custom form fields that you created will now appear on that product's page. Repeat the steps to enable the template on multiple products. You can use thebulk editorto enable your template on many products at once.