In Woocommerce I use Get the subcategories of the current product category in Woocommerce archives answer function, to display a list of subcategories on the parent category pages
But I only need to apply this to SPECIFIC product-categories though, and to use array with a hunch of category IDs seems not ideal.
I need to display the list only on the first children categories, so for example one of my main parent categories is "Clothing", then the subcategory "Shirts" and then the sub-sub-category "Sleeveless". I only need to display it on the first sub-categories, in this example "Shirts".