The Enrichment activity allows four links:
In the fourth option (a link):
Link definition: Allows the selection of the type of link and the target of the link. Link type includes:
Does each link definition establish a SQL right join from the filtering dimension (table) to the target table?
Or, does it establish a SQL right join except the third option:
"3. Define a link whose target may not exist in the database (0-1 relationship)). The join condition must be defined by 0 or 1 (max.) record in the target table."
...which sounds like it establishes a left join.
The relationship when enriching data is explained on this documentation: Enriching data
Hope this helps!
All the best,