Hello Prasath,
this is not a one-line-answer topic. But in a short, the best advice is that you follow the manual or the steps at the IBM site:
Migrating to Db2 13 - IBM Documentation
The migration is not difficult, the last catalog change is done at DB2 12 FL509, althought before moving to V13 you need to activate FL510.
Also you have posted it at the "Db2 Tools for zOS", I don't believe this be the right place, maybe that's the reason why your post got unnoticed.
Have you started with the preparation to migrate?
Thanks,