Safest pgupgrade jump distance

Hi, I was wondering what is the safest pg_upgrade version upgrade distance
going from 9.6 version. Do I need to go version by version or I can go from
9.6 to 15? We have a very huge database(TBs) with one replication server,
so we will first run the pgupgrade on the main server and then rsync to a
standby replica. I'm not sure whether it's safe to do it from 9.6 to 15 at
once, I have tested the process on 9,6 to 10 yet. Would that be a wise
approach to such an upgrade of the db?
Also, when upgrading a very big database with replication where none of the
data can be allowed to be lost, is the pgupgrade into rsync approach the
best one? Thanks.