How does one connect to a schema within a PDB (other than schema SYS)?

Using Oracle 18c on RedHat Linux 8

Connecting to CDB as ‘SYS’, I cannot figure out how to connect to a schema within the PDB other than as ‘SYS’. Maybe I don’t understand the CDB/PDB architecture well enough.

Here is what I have tried after logging into the Oracle 18c CDB as ‘SYS’ (using sqlplus sys as sysdba):

ALTER SESSION SET CONTAINER= PDB; conn myschema/mypasswd 

and I also tried (right from the CDB)

conn myschema/mypasswd@PDB; 

Both approaches fail to get me connected to the schema myschema in the PDB. That is, I am still ‘SYS’ in the PDB.

Are there any suggestions/explanations on how to resolve this? Do I have to setup some kind of access from the CDB-to-PDB for the schema myschema?