Hi,
Below is an example of SQL2 query based on your scenario. you can modify and use it
SELECT * FROM [nt:base] AS s WHERE ISDESCENDANTNODE([/content/geometrixx/en]) and (CONTAINS(s.[cq:tags], 'mynspace:mytag') or CONTAINS(s.[cq:tags], 'mynspace:mytagss1'))
where root node path and tags value you can change as per your need. Below is java formation
StringBuilder query = new StringBuilder();
query.append("SELECT * FROM [nt:base] AS s WHERE ISDESCENDANTNODE([")
.append(pathToYourPageArea) //for example /content/geometrixx/en
.append("]) AND (CONTAINS(s.[cq:tags],'mynspace:mytag') or CONTAINS(s.[cq:tags],'mynspace:mytagss1'))");
Query compiledQuery = queryManager.createQuery(query.toString(), Query.JCR_SQL2);
where 'mynspace:mytag' and 'mynspace:mytagss1' is an example and you can change it with variables
I hope it will help you to proceed. Let me know if you need more information.
Thanks,
Pawan