I mentioned previously the I had a little document written up, keep in mind this is how I did it on Bazzite so your mileage may vary but here it is.

To auto mount drives on Bazzite with KDE open terminal and type

(if you are using Gnome or already have Gnome disks installed you can skip to "open disks")

sudo rpm-ostree install gnome-disk-utility

Wait for-ev-er..................

Reboot

Open "disks"

Select your disk you want to auto mount

You'll see an icon that looks like a window with a play symbol in it that is "Additionaal Partition Options"

Click on it and select "Edit Mount Options"

You may or may not have to toggle user session defaults

Check the box that says mount on startup

Enter your password if asked and reboot to verify.