Disk usage limit for Time Machine not showing on Ventura

I'm setting up Time Machine for the first time on Ventura (13.5.2). When I add a disk, I get the options to encrypt and to add a password but I don't get the option to limit the disk usage. This is important for me as the backup is to a NAS and I don't want to fill it with Time Machine backups.

Any ideas? Is this feature limited to certain types of backup destinations?

The screen snip below is from the internet and shows the option that I am missing.

Thanks,

Dave