Upgrade PostgreSQL 9.6 to 10.6

Hello PostgreSQL Team,
I would like to know what would be the best way to do Database migration
from PostgreSQL 9.6 engine to 10.6 by creating a new cluster in 10.6 and
then copy data.

Size of the cluster is 3.8 TB.

1) It would be a new cluster we want to create on 10.6 and then copy data
form 9.6 and shutdown 9.6
2) Cluster today contains 1 master instance and another instance for reader
3) Can this be done without a downtime ?  what are the options I have to do
this without making this complicated . We have about 30 -40 tables to do
the migration.

Appreciate your replies.

Thanks,
Kranthi