about nfs mount command

I'm new to NetApp, but let me ask you the following questions.

I bought the FAS2750 and I don't have it yet, but the Ontap version is probably 9.8 or higher.

Now, I am making an NFS mounting from linux (rhel7) to another NAS storage with the following command.
#FSTAB command
<MountServer>:/mnt/Dir1 /mnt/Dir1 nfs4 default,soft 0 0

When changing from NAS to FAS2750, Linux will also be upgraded from 7 to 8.
If so, please give me some advice on how to change this command.

Assuming the following command, I don't know whether 4.1 or 4.2 is the correct answer for nfsvers = 4.X.
<MountServer>:/mnt/Dir1 /mnt/Dir1 nfs default,soft nfsvers=4.X 0 0

Thanks