I just flashed a used Tab S5e and the docs here were sorely lacking. The documentation doesn’t mentioned odin / heimdall flashing tools at all. This device doesn’t support fastboot from what I can tell, and thats what the docs recommend. It seems like it needs to be re based on the lineageOS docs here. https://wiki.lineageos.org/devices/gts4lvwifi/install
I tried getting heimdall to work instead but had to use Odin.
Additionally I discovered that Samsung mysteriously hides the “OEM Unlock” option in the developer options for seven days. I was able to use method one here to restore it: https://www.droidwin.com/fix-missing-oem-unlock-samsung/