The "modern" way would use systemd to implement the mounting, either on a system or a user level. Using fstab can be problematic when the drive is missing or otherwise not available during boot.
Not sure what KDE uses exactly for auto mounting.
What's used under the hood for this is udisks, the same thing used by other file managers to achieve mounting capabilities. It allows you to mount devices without needing to mess with something cryptic and archaic like fstab and doesn't require root.
You can always keep using fstab of course since it works, but in that case you probably also want to use fstab systemd integration.
The KDE auto mount never worked on plasma 6
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