https://www.ibm.com/docs/en/db2/11.5.x?topic=commands-db2iupgrade-upgrade-instance
db2iupgrade - Upgrade instance command
Upgrades an instance to a Db2 copy of the current release from a Db2 copy of a previous release. The Db2 copy from where you are running the db2iupgrade...
upgradeinstancecommand