Lenovo sometimes provides stock firmware on their support site.
For those still using this tablet, there are two primary paths: checking for the final official OTA (Over-the-Air) updates or turning to the enthusiast community for custom ROMs. Official Android Support Status Official manufacturer support for the Lenovo TB-X704F lenovo tbx704f android update 2021
(Rooting) were the primary methods used in 2021 to "update" these devices to modern standards. How to Check Your Version Today Lenovo sometimes provides stock firmware on their support
Installing the LineageOS zip file and "GApps" (Google Apps) for the Play Store. Verdict for 2021 lenovo tbx704f android update 2021