Here is a tutorial on how to root a Samsung Galaxy Tab S3 using Magisk Manager and TWRP.
Links :
SM-T820 Firmware :
www.sammobile.com/samsung/gal...
Odin :
odindownload.com/download/#.X...
TWRP for Tab s3 :
androidfilehost.com/?fid=9623...
Magisk Manager APK :
magiskroot.net/magisk-manager...
Tab S3 Encryption Disabler :
androidfilehost.com/?fid=8902...
SDK Plateform Tools :
developer.android.com/studio/...