Download the firmware, and extract "boot.img.lz4" from AP.
Use 7-zip or something else to compress the boot file and choose TAR format.
Use Magisk to patch the "boot.img.tar", and you will get "magisk_patched.tar" in /Download folder.
Flash it as AP and wipe user data. (You should unlock the bootloader.)
Then you have successfully rooted your device.
How to download the firmware.
Use Samfirm to search device model and CSC code.
It seems that Sammobile has not released the firmware of the new Galaxy Tab S7 series.
Use 7-zip or something else to compress the boot file and choose TAR format.
Use Magisk to patch the "boot.img.tar", and you will get "magisk_patched.tar" in /Download folder.
Flash it as AP and wipe user data. (You should unlock the bootloader.)
Then you have successfully rooted your device.
How to download the firmware.
Use Samfirm to search device model and CSC code.
It seems that Sammobile has not released the firmware of the new Galaxy Tab S7 series.