OK a Connection pool stores JDBC Connection objects, so an ORM needs a JDBC Connection to connect to the database. The ORM products themselves do not create these Connections or pools, It gets them from a Connection Pool. So the ORM requires you to configure a connection pool. Hibernate for instance, comes with C3PO, which you can configure the pool in the hibernate.cfg.xml.
Unfortunately, I do not know what TopLink comes with, so I can't tell you which Connection Pool implementation it uses.
If you are deploying in say An App Server, then you can create a DataSource and that would use/create a Container created ConnectionPool.