e.g. changing the DBID and Database Name

e.g.
Backup database
RMAN> backup database

Mount database
SQL> shu immediate;
SQL> startup mount;

Change DBID
$ nid TARGET=SYS

or

Change both DBID and DBNAME
$ nid TARGET=SYS DBNAME=new_xe

Change database name from parameter file (init.ora)
*.db_name='NEW_XE'

Mount database again
SQL> startup mount;

Open database
SQL> alter database open resetlogs;

Ref: https://docs.oracle.com/database/121/SUTIL/GUID-05B4733C-9EAA-438F-A2A4-4E84EB1E1E65.htm#SUTIL1544s