We have a few themes support Shopify 2.0, you need to follow the instruction below to know how to configure Custom Metafield for your Products.
To configure the Metafield for your products, please go to Dashboard Settings > Custom Data > Select type of Metafield > Add definition button to start configuring Metafield. Kindly follow my video below:
If you wanna add a Countdown option for each product – with a different time, you can configure to use the Metafield Countdown for your products.
You need to configure some options below:
Name: You can add any name here. Example: Product Metafield Countdown.
Namespace and key: This is a required option, you have to add theme.countdown key here.
Description: You can add any text to the description.
Select Content Type: This is a required option, you have to choose Date and time > One value

Click Save button and then you will get the option below:

In Shopify backend > Products > All Products > open the product that you wanna add the Metafields Countdown.
You guys can follow the video below:
Please follow my video below to know how to add the Metafields Countdown on Customize > Products page.
With all the rest products that you do not configure the Metafield Countdown, the countdown Timer still show if you configure the Countdown Timer Loop in a day in the Product Page > Countdown Timer option:

And choose All products here:

If you only want to show the Countdown Timer option on the Product page with the Product that has been configured Metafield Countdown, you should remove the Time Settings here:

If you wanna add an External/ Affiliate button for each product, you can configure to use the Metafield - External/ Affiliate for your products.
You need to configure some options below:
Name: You can add any name here. Example: External Title.
Namespace and key: This is a required option, you have to add theme.external_title key.
Description: You can add any text for the description.
Select Content Type: This is a required option, you have to choose Text > Single line text > One value

You need to configure some options below:
Name: You can add any name here. Example: External Link.
Namespace and key: This is a required option, you have to add theme.external_link key.
Description: You can add any text for the description.
Select Content Type: This is a required option, you have to choose URL > One value

After configuring is done, we will get 2 Metafield definitions as the image below:

In Shopify backend, go to Products > All Products option and open the product that you wanna add the Metafields External/ Affiliate button. Please follow this video:
And when you view the product, you will see the External/ Affiliate button shown as the image below:

You can learn more this article.
You can learn more this article.
You can learn more this article
You need to configure some options below:
Name: You can add any name here. Example: Estimate Start Date.
Namespace and key: This is a required option, you have to add theme.estimateStartDate key.
Description: You can add any text for the description.
Select Content Type: This is a required option, you have to choose Number > Integer > One value

You need to configure some options below:
Name: You can add any name here. Example: Estimate End Date.
Namespace and key: This is a required option, you have to add theme.estimateEndDate key.
Description: You can add any text for the description.
Select Content Type: This is a required option, you have to choose Number > Integer > One value

After configuring, we will get 2 Metafield definitions as the image below:

Go to Products > Open the Product that you wanna add the Metafields Delivery. Kindly follow this video to add the Metafield Delivery Start/ End for the product.
You can follow my image below:

Example: Today is October 11, 2022 and I set the start date for delivery as the next 2 days, it's October 13. And the End date of delivery is the next 4 days, it's October 15, 2022.
NOTE: This guideline is for Kalles 4, Gecko 6, Unsen and Ocolus themes.
If you use Ecomus and Kalles 5 theme, please follow this guide
You need to configure some options below:
Name: You can add any name here. Example: Custom Badge.
Namespace and key: This is a required option, you have to add theme.custom_badge key here.
Description: You can add any text for the description.
Select Content Type: This is a required option, you have to choose Text > Single line text > One value or Multi-line text > One value

Then click Save button to save all changes, we will get the metafield definition as the image below:

In Shopify backend, go to Products > All Products > open the product that you wanna add the Product Custom Badge. In the product, please scroll down to the bottom of the page, you will see the Product Custom Badge metafield option. Kindly follow the video below:
If you want to have many badges in one product, use ; to seperate the badges. Example: Best seller; New
In Shopify backend, click the Customize button to go to Theme Settings > Products > Scroll to Badges option > Tick on the Use custom badge checkbox > The custom badge will show as the image below:

You can show the additional image(not product image) on a section of product page.
You need to configure some options below:
Name: You can add any name here. Example: Custom Image.
Namespace and key: you can add any key here. Example: theme.custom_image
Description: You can add any text for the description.
Select Content Type: This is a required option, you have to choose File > One file.

In Shopify backend > Products > open the product that you wanna add the Product Custom image. In the product, please scroll down to the bottom of the page, you will see the Custom Image metafield option. Then choose the image you wanna show for this product.

Go to Theme > Customize > Product page > Add section you want to show the image.
For example: "Image with text" section.

Click on "Connect dynamic source" > choose "Custom Image"

Then the image will show on the product page

You can show the additional image(not product image) inside Product Main block on product page.
You need to configure some options below:
Name: You can add any name here. Example: Custom Image 2.
Namespace and key: you can add any key here. Example: theme.custom_image2
Description: You can add any text for the description.
Select Content Type: This is a required option, you have to choose Multi-line text.

In Shopify backend > Content > Files > upload the image and click on "Copy link"

Go to Products > open the product that you wanna add the Product Custom image. In the product, please scroll down to the bottom of the page, you will see the Custom Image 2 option. Then paste the image link you just copied > Save

Go to Theme > Customize > Product Page > Product Main > Add block > Custom Liquid > add the code with this syntax:
<img src="{{ product.metafields.the_key_for_metafield }}" width="300">
the_key_for_metafield is the namespace and key which you create at first step.
For example: <img src="{{ product.metafields.theme.custom_image2 }}" width="300">
Then the image will show inside Product main section.

10.1. Add Product Metafield Product stock
You need to configure some options below:
Name: You can add any name here. Example: Product Stock.
Namespace and key: This is a required option, you have to add theme.product_stock key here.
Description: Add the text: "Products sold / Total products".
Select Content Type: This is a required option, you have to choose Single line text > One value

Then click Save.
10.2. Configure Metafield in Products