I got a Lenovo TAB6 (A101LV) and rooted it, so I’m leaving a note.
Please do this at your own risk as there is a possibility of bricking the device.

Also, since this is a personal note, detailed explanations are not provided.

Enable USB Debugging

1. “Settings” => “System” => “About tablet” => “Build number”
   Tap the build number 7 times to enable “Developer options”.

2. “Settings” => “System” => “Developer options” => Enable “USB debugging”.

Bootloader Unlock

Reboot into the bootloader

$ adb reboot bootloader

$ fastboot flashing unlock

Select “UNLOCK THE BOOTLOADER” and confirm with the power button.

Successfully unlocked the bootloader.

Extract boot.img and Install Magisk

I referred to this site. https://smartasw.com/archives/15704

=> Successfully installed Magisk and obtained root access.

It’s better to apply Magisk to boot_b.img.

Command Memo (Command memo for reference)

• Download GSI

$ aria2c -k 10M -x 10 https://github.com/phhusson/treble_experimentations/releases/download/v416/system-squeak-arm64-ab-vanilla.img.xz

• Extract xz file

$ xz -d system-squeak-arm64-ab-vanilla.img.xz

• Push img

$ adb push system-squeak-arm64-ab-vanilla.img /storage/emulated/0/Download/

• GSI DSU-Sideloader install

$ adb shell ' sh "/storage/emulated/0/DSU/workspace_dsuhelper/install" '

• boot.img

$ adb shell
$ su
# cd /dev/block/bootdevice/by-name/
# mkdir /sdcard/backup_img
# for file in *; do
    if [[ "${file}" = boot* ]]; then dd if=/dev/block/bootdevice/by-name/"${file}" of=/sdcard/backup_img/"${file}".img ; else continue ; fi
done

• Pull boot.img

$ adb pull /sdcard/backup_img/boot_a.img .
$ adb pull /sdcard/backup_img/boot_b.img .

• Reboot

$ adb reboot

• Push boot.img

adb push boot_*.img /storage/emulated/0/Download/

• Pull magisk.img

adb pull /storage/emulated/0/Download/magisk_patched-25200_yf1VS.img .

• Reboot into bootloader

$ adb reboot bootloader

• Flash boot.img

$ fastboot flash boot magisk_patched-25200_yf1VS.img

• Reboot

$ fastboot reboot