Convert Oracle 12c Tables from BYTES to CHAR

Convert Oracle 12c Tables from BYTES to CHAR
I want the tables be converted from BYTE to CHAR on 12.1.0.
I am doing a export dump from a non-Unicode database and the Varchar2 data types is in BYTES (Which is the default).
The import I am doing on is a UNICODE database but import dump is Keeping the same data type as in the source.
Is there a way to change the NLS_LENGTH_SEMANTICS set as CHAR and do the export?
or ; I have to change the NLS_LENGTH_SEMANTICS to CHAR on the target as well?
I am not sure if this will work?

Source:=
SQL> desc PS_GVT_POI_TBL
 Name                                                                                Null?    Type
 ----------------------------------------------------------------------------------- -------- ------------------
SETID                                                                               NOT NULL VARCHAR2(5)
GVT_POI                                                                             NOT NULL VARCHAR2(4)

The result I am looking should look like this (below):=
SQL> desc PS_GVT_POI_TBL
 Name                                                                                Null?    Type
 ----------------------------------------------------------------------------------- -------- ------------------
 SETID                                                                               NOT NULL VARCHAR2(5 CHAR)
 GVT_POI                                                                             NOT NULL VARCHAR2(4 CHAR)