Can you connect as SYSDBA without password into a PDB directly? Of course with the usual way of “sqlplus / as sysdba”. Yes you can, even without no bequeath connection available.
There is a 19c EBS notes.
In one of the most important EBS MOS Notes: 2552181.1 – Interoperability Notes: Oracle E-Business Suite
MOS Notes: 2552181.1 – Interoperability Notes: Oracle E-Business Suite Release 12.2 with Oracle Database 19c under section 2.5 you can read: