List the parameter which modified in PDB database.

Set the container or PDB:

ALTER SESSION SET CONTAINER=pdbname;

Check the list of parameter which able to modified for PDB database:

SELECT NAME FROM V$SYSTEM_PARAMETER WHERE ISPDB_MODIFIABLE = ‘TRUE’
 ORDER BY NAME;

Change the value of parameter for PDB database:

-- Check the con_name
SHOW CON_NAME
-- Alter the PGA target only at current PDB which show with above command
ALTER SYSTEM SET PGA_AGGREGATE_TARGET=10G SCOPE = SPFILE;

Check the value of all PDB or CDB parameters:

SELECT NAME, VALUE, DISPLAY_VALUE, CON_ID FROM V$SYSTEM_PARAMETER
 WHERE NAME = 'PGA_AGGREGATE_TARGET' ORDER BY NAME;