Ingredient Highlights

Name: Ingredient Highlights
Namespace and key: custom.ingredient_highlights
Type: Multi-line text

In product setting:

Result:

Choosing the metafield (version 1.3.0)

The Compare products section reads this content through its Ingredient highlights metafield setting. The default key is custom.ingredient_highlights.

Keep the default key above and it works with no extra setup.
Or rename it: create the metafield under your own namespace.key (for example, your brand name), then set Ingredient highlights metafield to match.
Reuse on one page: create one metafield per copy (for example custom.ingredient_highlights and custom.ingredient_highlights_2) and point each Ingredient highlights metafield at its own key to show different content.

See How to setup Metafield in version 1.3.0? for details.