You must manually add undo and redo logs, unless you store your policy-managed database on Oracle Automatic Storage Management (Oracle ASM) and Oracle Managed Files is enabled.
If there is space in a server pool to add a node and the database has been started at least once, then Oracle Clusterware adds the Oracle RAC database instance to the newly added node and no further action is necessary.
Note:
The database must have been started at least once before you can add the database instance to the newly added node.
If there is no space in any server pool, then the newly added node moves into the Free server pool. Use the srvctl modify srvpool command to increase the cardinality of a server pool to accommodate the newly added node, after which the node moves out of the Free server pool and into the modified server pool, and Oracle Clusterware adds the Oracle RAC database instance to the node.