Our target is to extend the native Joomla category blog with a predefined custom field as a filter. In our case, the custom field "tags" has the ID 18 and contains 3 values.
Due to the very complex structure of the site, we rather prefer to solve this with a new custom field filter instead of the native tags.
Hint: In the following article, user "pepperstreet" suggests to extend the "table layout header". How can this be achieved? https://www.joomlashack.com/blog/joomla/custom-category-layout/