You will now be able to do all sorts of mods and root Tab S3 as TWRP custom recovery is available for download for this Samsung android tablet. Available for both SM-T820 and T825 models, this TWRP custom recovery is v184.108.40.206 which is the latest version available right now.
While Tab S3 TWRP recovery is still in beta state, everything is working as expected. Only the F2FS support is missing and the developers behind TWRP are working hard to add it in upcoming release but other than that, everything is working.
List of what is working – MTP working; ADB working; SEANDROID warning fix; TWRP and Kernel built from latest source; NTFS support and TWRP app support.
Before you start, go to settings > developer options > OEM unlocking. If you do not see developer options, go to about and press build number few times. To flash TWRP for Tab S3, download the flashable TWRP file from here. Download ODIN as well. Fire it p and put the TWRP file in AP. Then put the S3 in download mode by pressing vol down and power button together for few seconds.
Connect your android tablet to the computer and click on the Start button to commence the flashing process. It will take only a few seconds for the flashing to complete. Reboot and do whatever you want to do with it.