DDD: Do categories, tags, or aggregate likes belong to the domain?

Question

PHP

Looking at one side, do these elements just help the user interact with the interface (filter in case of categories or tags, express opinion in case of likes) with aggregates, and not change their state? That is, logically, all this refers to the application layer (or UI in general) and can be placed in its separate services that do not intersect with the domain in any way?
And if, on the other hand, an aggregate (let's say an article) can have only one category, or a user can like a certain message on the forum only once - and this is business logic and should be allowed in the aggregate itself, domain service or team.
Help me to understand)