Samsung Galaxy Tab S3 LTE (gts3llte, SM-T825)] / Samsung Galaxy Tab S3 WiFi (gts3lwifi, SM-T820)] for eOS-S 1.21:
Galaxy Tab S3 LTE (gts3llte, SM-T825)]
e-1.21.1-s-20240401-UNOFFICIAL-gts3llte.zip
https://sourceforge.net/projects/eosbuildsronnz98/files/SamsungSmartphones/e-1.21.1-s-20240401-UNOFFICIAL-gts3llte.zip/download
Galaxy Tab S3 WiFi (gts3lwifi, SM-T820)]
e-1.21.1-s-20240331-UNOFFICIAL-gts3lwifi.zip
https://sourceforge.net/projects/eosbuildsronnz98/files/SamsungSmartphones/e-1.21.1-s-20240331-UNOFFICIAL-gts3lwifi.zip/download
Please see sources and install instructions including recovery here:
https://xdaforums.com/t/rom-unofficial-12l-eas-ota-sm-t820-sm-t825-2023-11-15-lineageos-19-1-for-galaxy-tab-s3.4418855/
Use it at your own risk!
Please support the developer(s)!